Para-atrial non-acute mediastinal hematoma after left atrial maze procedure mimicking tumor in a patient with treated melanoma.

INTRODUCTION: The Cox Maze III procedure is considered the gold standard open surgical procedure for management of atrial fibrillation. This article outlines a unique case of a para-atrial mediastinal hematoma following a bilateral thoracoscopic left atrial Maze procedure mimicking malignancy. REPORT: A 60-year-old male, with past history of melanoma, underwent bilateral thoracoscopic left atrial mini maze procedure with radiofrequency energy and exclusion of the left atrial appendage. Seven months later, a chest computed tomography (CT) scan was performed to evaluate for pulmonary embolism. The CT scan unexpectedly showed an ill-defined, heterogeneous para-atrial mass immediately superior to the left atrium concerning for tumor and mediastinal adenopathy. The mass was moderately hypermetabolic on subsequent 2-[fluorine-18]fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) scan. A follow-up PET/CT three months later demonstrated near-complete resolution of the para-atrial mass with minimal residual hematoma. CONCLUSION: Non-acute mediastinal hematoma following a maze procedure can potentially be confused with a tumor mass and/or lymphadenopathy on CT and FDG PET/CT. With knowledge of the potential for false-positive FDG uptake in a hematoma, the lesion was monitored, and unnecessary biopsy was avoided.

Gd-DISIDA--a potential contrast agent for magnetic resonance imaging of the hepatobiliary system.

Gadolinium (Gd) labeled diisopropyliminodiacetic acid (DISIDA) was prepared by mixing a Gd solution and a DISIDA solution in appropriate proportions and at controlled pH. Optimal complexation was obtained at a Gd:DISIDA molar ratio of 1:2.5 and the pH of the final solution was 7.3 to 7.5. The complex was found to be stable both in vitro and in vivo. Gd-DISIDA (12.5 mumol/kg) was injected into mice, and T1 and T2 relaxation times of various tissues were measured and compared with those of normal tissues. Only the T1 values of the blood and the liver markedly decreased after Gd-DISIDA administration and also the reduction in T1 values depended on the dose of Gd-DISIDA. Magnetic resonance imaging of the rabbit liver showed considerable contrast enhancement at 30 minutes after administration of 12.5 mumol/kg of Gd-DISIDA.