Polyposis syndromes of the gastrointestinal tract: MR findings.

We describe the magnetic resonance (MR) findings in patients with gastrointestinal polyposis syndromes using breath-hold T1-weighted sequences, both standard and with fat suppression, prior to and following gadolinium administration, and breathing-independent single-shot half-Fourier RARE T2-weighted sequences. Six patients with gastrointestinal polyposis syndromes underwent MR examination to investigate for the presence of metastatic disease. The appearances of the gastrointestinal polyps on noncontrast T1-weighted spoiled gradient-echo (SGE), T2-weighted (half-Fourier RARE) images, and early and late gadolinium-enhanced SGE images were determined. Other gastrointestinal findings and extragastrointestinal disease were also evaluated. Patients with the following gastrointestinal polyposis syndromes were included: familial polyposis (n = 3), Peutz-Jeghers syndrome (n = 1), Gardner's syndrome (n = 1), and neurofibromatosis (n = 1). Polypoid lesions in all patients exhibited signal intensity comparable to bowel on noncontrast images and enhanced similar to bowel on early and late gadolinium-enhanced images. Polyps larger than 2 cm, observed in one patient with familial polyposis and the patient with Gardner's disease, showed mild heterogeneity on late gadolinium-enhanced fat-suppressed images. Multiple colonic polyps ranging from 5 mm to 3 cm in diameter were observed in patients with familial adenomatous polyposis. A solitary 1.5 cm polyp associated with entero-enteric intussusception was observed in the patient with Peutz-Jeghers syndrome. Gastric polyps ranging from 5 mm to 6 cm were observed in the stomach of the patient with Gardner's syndrome. Duodenal and jejunal neurofibromas ranging from 1 to 2 cm in diameter were present in the patient with neurofibromatosis. Extra gastrointestinal findings included an adrenal adenoma (1 patient), a pheochromocytoma (1 patient), and liver metastases (2 patients). Gastrointestinal polyps in patients with polyposis syndromes may be visualized on MR images employing breath-hold T1-weighted and breathing-independent snapshot T2-weighted techniques. Appreciation of polyp enhancement on post-gadolinium images is an important finding, which should help distinguish polyps from bowel contents.