Metastasis to the pancreas: characterization by morphology and contrast enhancement features on CT and MRI.

AIMS: To investigate the characteristics of metastasis to the pancreas using computed tomography (CT) and magnetic resonance imaging (MRI). METHODS: Twenty-two patients with metastases to the pancreas were examined preoperatively by MRI (7/22) and/or multidetector CT (15/22). Pre- and post-contrast images were acquired and morphology, size, and contrast enhancement of the tumor analyzed. Subsequently, all patients underwent surgery, and the histopathologic findings were compared with the imaging results. RESULTS: In 22 patients, a total of 29 metastases were found on CT and MRI. These metastases originated from renal cell carcinomas (RCC; 22/29), colorectal carcinoma (3/29), and other malignancies (4/29). The metastases differed not in size or location, but in their contrast enhancement characteristics. RCC metastases had either intense homogeneous enhancement (in small lesions) or rim enhancement (in large lesions). Outer regions of colorectal metastases showed no difference from normal pancreatic tissue, whereas the inner area showed hypo-enhancement due to central necrosis. CONCLUSION: Imaging features of metastases from RCC point to their primary origin. While they can be distinguished from primary adenocarcinoma of the pancreas, differentiation from endocrine carcinoma might be difficult. Differentiation of colorectal carcinoma remains to be investigated on larger numbers of cases.

The long term myotoxic effects of bupivacaine and ropivacaine after continuous peripheral nerve blocks.

UNLABELLED: Compared with bupivacaine, acute myotoxicity of ropivacaine is less severe. Thus, in this study we compared the long term myotoxic effects of both drugs in a clinically relevant setting. Femoral nerve catheters were inserted in anesthetized pigs, and either 20 mL of bupivacaine (5 mg/mL) or ropivacaine (7.5 mg/mL) was injected. Subsequently, bupivacaine (2.5 mg/mL) and ropivacaine (3.75 mg/mL) were continuously infused (8 mL/h) over 6 h. Control animals were treated with corresponding volumes of normal saline. After 7 and 28 days, respectively, muscle samples were dissected at the former injection sites, and histological patterns of muscle damage were blindly scored (0 = no damage to 3 = marked lesions/myonecrosis) and compared. No morphological tissue changes were detected in control animals. In the observed period, both local anesthetics induced morphologically identical patterns of calcific myonecrosis, formation of scar tissue, and a marked rate of fiber regeneration. However, bupivacaine's effects were constantly more pronounced than those of ropivacaine. These data show that both drugs induce irreversible skeletal muscle damage in a clinically relevant model, and confirm the exceeding rate of myotoxicity of bupivacaine. However, the clinical impact of these long term myotoxic effects still has to be assessed. IMPLICATIONS: In a period of 4 wk after peripheral nerve block, both long-acting local anesthetics, bupivacaine and ropivacaine, produced calcific myonecrosis suggestive of irreversible skeletal muscle damage. In comparison with ropivacaine, however, the extent of bupivacaine-induced muscle lesions was significantly larger.

The acute myotoxic effects of bupivacaine and ropivacaine after continuous peripheral nerve blockades.

UNLABELLED: Bupivacaine causes muscle damage. However, the myotoxic potency of ropivacaine is still unexplored. Therefore, we performed this study to compare the effects of bupivacaine and ropivacaine on skeletal muscle tissue in equipotent concentrations. Femoral nerve catheters were inserted into anesthetized minipigs, and 20 mL of either bupivacaine (5 mg/mL) or ropivacaine (7.5 mg/mL) was injected. Subsequently, bupivacaine (2.5 mg/mL) and ropivacaine (3.75 mg/mL) were continuously infused over 6 h. Control animals were treated with corresponding volumes of normal saline. Finally, muscle samples were dissected at injection sites. After processing and staining, histological patterns of muscle damage were blindly examined, scored (0 = no damage to 3 = myonecrosis), and statistically analyzed. After normal saline, only interstitial edema was found. Bupivacaine treatment caused severe tissue damage (score, 2.3 +/- 0.7), whereas ropivacaine induced fiber injury of a significantly smaller extent (score, 1.3 +/- 0.8). Furthermore, bupivacaine, but not ropivacaine, induced apoptosis in muscle fibers. In summary, both drugs induce muscle damage with similar histological patterns. Compared with bupivacaine, which induces both necrosis and apoptosis, the tissue damage caused by ropivacaine is significantly less severe. We conclude that ropivacaine's myotoxic potential is more moderate in comparison with that of bupivacaine. IMPLICATIONS: After continuous peripheral nerve blockades, the long-acting local anesthetics bupivacaine and ropivacaine both induce fiber necrosis in porcine skeletal muscle tissue. In comparison with ropivacaine, bupivacaine causes tissue damage of a significantly larger extent and additionally induces apoptosis in skeletal muscle cells.