MR imaging with spatial modulation of magnetization in the evaluation of chronic central pulmonary thromboemboli.

Abstract

To assess the diagnostic value of magnetic resonance (MR) imaging with SPAMM (spatial modulation of magnetization) in the identification of chronic central pulmonary thromboemboli. Twelve patients with pulmonary hypertension and five healthy volunteers were prospectively studied with a 1.5-T MR imaging system. The SPAMM technique was integrated into a conventional cardiac-synchronized spin-echo (SE) sequence. Six of the 12 patients had central thromboemboli. In the healthy subjects, intravascular stripes in the central pulmonary arteries disappeared as a result of flow within 100 msec after the R wave. Areas of persistent stripes were identified in seven of eight central pulmonary arteries with thromboemboli. Conversely, in the 16 central pulmonary arteries without clot, intraluminal stripes disappeared despite the presence of flow-related signal (sensitivity = 88%, specificity = 100%, accuracy = 96%). SPAMM appears to be a simple and effective technique for differentiating central pulmonary arterial thromboemboli from flow-related signal frequently observed with pulmonary hypertension.