ABSTRACT
Intraperitoneal gelatin sponge can mimic a mass lesion on magnetic resonance (MR) images. To determine the MR imaging characteristics of gelatin sponge over time, a 15 x 10 x 4-mm piece of gelatin sponge soaked in saline was surgically implanted in the peritoneal cavity of 14 mice. Two mice underwent a sham operation. Contiguous axial spin-echo images of the abdomen were obtained with T1-weighted, spin-density, and T2-weighted sequences preoperatively and over a 6-week period postoperatively. Gelatin sponge initially appears as a heterogeneous mass of low signal intensity on T1-weighted images and increasing intensity on spin-density and T2-weighted images, containing multiple round foci of very low signal intensity, attributable to air, at all sequences. Over time, signal intensity further increases and becomes more homogeneous on spin-density and T2-weighted images, although foci of air persist to 3 weeks. By 2-4 weeks, the mass is no longer discrete. Foci of air should help differentiate gelatin sponge from tumor and add gelatin sponge to the differential diagnosis of abscess.
Subject(s)
Gelatin Sponge, Absorbable , Magnetic Resonance Imaging , Peritoneal Cavity/pathology , Surgical Sponges , Animals , Female , MiceSubject(s)
Blood Substitutes , Blood Volume Determination/methods , Fluorine , Fluorocarbons , Magnetic Resonance Spectroscopy/methods , Animals , Blood Substitutes/analysis , Blood Volume , Fibrosarcoma/metabolism , Fibrosarcoma/physiopathology , Fluorocarbons/analysis , Leukemia L1210/metabolism , Leukemia L1210/physiopathology , Liver/blood supply , Liver Neoplasms, Experimental/metabolism , Liver Neoplasms, Experimental/physiopathology , Lymphoma/metabolism , Lymphoma/physiopathology , Mice , Oxygen/metabolism , Oxygen/pharmacokinetics , Spleen/blood supply , T-LymphocytesABSTRACT
The feasibility of combined magnetic resonance (MR) imaging and surface coil phosphorus-31 MR spectroscopy at 1.5 T was examined in a clinical study of 34 patients before biopsy of bone or soft-tissue lesions of the extremity and trunk. The results confirmed the inability of MR imaging alone to distinguish most benign lesions from malignant ones. Malignant lesions were distinguished from benign lesions on the basis of significantly higher mean peak ratios of phosphomonoester (PME) to beta-nucleoside triphosphate (NTP) and of phosphodiester to NTP, a significantly lower mean peak area ratio of phosphocreatine to NTP, and a higher mean pH. The diagnostic performance of the PME/NTP peak area ratio is characterized by a sensitivity (true-positive fraction) of 1.00 and a specificity (true-negative fraction) of 0.93. This study provided preliminary evidence that P-31 MR spectroscopy may be used to improve diagnostic specificity in bone and soft-tissue lesions.
