Ingested fish bones can cause a school of problems

Avoiding the TRAP: diagnostic imaging of the twin reversed arterial perfusion and image-guided ablation. (Provided by Dave Roy)

Radiologists must become more alert to the extensive range of health problems faced by patients who swallow fish bones, according to a thought-provoking poster from Spain that was one of eight international exhibits to scoop a prestigious Magna Cum Laude award in the vast RSNA 2007 poster hall on Wednesday afternoon.

In about 1% of cases, ingested foreign bodies cause gastrointestinal perforation. Injury may occur anywhere from the mouth to the anus, but is most common in the small bowel, said researchers from the Hospital Clinico Universitario de Santiago de Compostela."There may be a lag of months or years between ingestion and the onset of symptoms." said lead author A. Martinez de Alegria. "Obscure history and nonspecific presentation make diagnosis of dietary foreign-body perforation extremely difficult."Among the possible complications of GI perforation are abscess formation, penetration through nearby organs or vessels, distant migration, and eventual surfacing to the skin. Problems are most common in children and the elderly, and predisposing factors include eating rapidly and wearing dentures, which eliminate tactile sensation on the palatal surface.The most opaque, and therefore easy to see, fish bones on x-ray are cod, hake, haddock, and lemon sole. The least opaque are herring, mackerel, sardine, and salmon. CT is very useful in locating esophageal fish bones, even those not visible on x-ray, and in finding complications.Imaging of twin-reversed arterial perfusion was the focus of another award-winning Magna Cum Laude exhibit by Dr. Dave Roy, a radiologist from the University of Texas Southwestern Medical Center in Dallas. This condition affects monozygotic twin pregnancies in which a donor (pump) twin completely assumes the cardiac demands for both itself and its recipient (acardiac) twin.In this unusual syndrome, the pump twin provides blood to the acardiac fetus via a vascular anastomosis in their shared placenta. The circulatory burdens of both fetuses may eventually overwhelm the pump twin's heart, resulting in a host of problems: congestive heart failure, polyhydramnios, premature delivery, and even fetal death. Early diagnosis and careful evaluation are paramount in these cases because options are available to preserve the pump twin, including radiofrequency ablation, Roy said.Dr. Declan Sheppard of Portiuncula Hospital in Ballinasloe, Galway, Republic of Ireland, received a top award for his sonographic primer and quiz of benign and malignant axillary lymph nodes in breast cancer. The exhibit is designed to help radiologists to differentiate benign and malignant nodes and enable them to identify those nodes requiring biopsy. Among the sonographic features with a high positive predictive value for malignancy are short axis >1 cm (88%), cortical rim >0.5 cm (87%), hilar displacement (87%), hilar compression (87%), lobulation (86%), long axis >2 cm (81%), and L/S ratio <2 (77%)."There is no single sonographic feature that is 100% specific for malignancy or benignity," he said. "There are, however, sonographic features that are suggestive of malignancy or benignity. Combinations of a number of their features may suggest malignancy or benignity and may help in guiding biopsy."

Five others were recipients of the Magna Cum Laude:

• Dr. Dhawal Goradia, University of Washington, Seattle
• Dr. Patricia Martin, Hospital Universitario 12 de Octubre, Madrid, Spain
• Dr. Daniel Vinócur, Miami Children's Hospital
• Dr. Hironobu Sou, University of Yamanashi, Japan
• Dr. Kirkland W. Davis, University of Wisconsin School of Medicine and Public Health, Madison