Magnetic resonance imaging for diagnosis of parotid malignant tumors and the pathological basis / 南方医科大学学报

<p><b>OBJECTIVE</b>To investigate magnetic resonance imaging (MRI) features of parotid malignant tumors and study their pathological basis.</p><p><b>METHODS</b>Forty-seven patients with parotid malignant tumors confirmed by surgery (41 patients) or biopsy (6 patients) were enrolled in this study. A comparative analysis was conducted of the pathological and MRI findings in 30 patients with the entire lesions available. Each of the MRI features was analyzed retrospectively and the typical MRI findings of common parotid malignant tumors were summarized.</p><p><b>RESULTS</b>MRI allowed accurate diagnosis of parotid malignant tumors. Four patients with low-grade mucoepidermoid carcinoma showed well-defined tumor margin and were difficult to distinguish from benign tumors. Six patients with high-grade mucoepidermoid carcinoma had obscure margin of the tumor which easily underwent necrosis with liable lymph node involvement. The 8 cases of adenoid cystic carcinoma was characterized by extensive invasion surrounding the parotid gland. Most of 8 cases of malignant pleomorphic adenoma still showed high and heterogeneous signal on T2WI, with irregular shape and poorly defined margin. Nine cases of lymphoma all had secondary lesions characterized by extensive involvement and presence of multiple nodules. The 4 cases of acinic cell carcinoma showed either regular or irregular tumor morphology, presenting with high signal intensity on T1WI and T(2)WI.</p><p><b>CONCLUSION</b>MRI is an important modality for the diagnosis of parotid malignant tumors. Most of the common parotid malignant tumors have characteristic MRI and pathological features, which make possible their differential diagnosis.</p>

Value of magnetic resonance imaging in displaying the parotid gland segments of the facial nerve / 南方医科大学学报

<p><b>OBJECTIVE</b>To evaluate the value of magnetic resonance imaging (MRI) in displaying the parotid gland segments of the facial nerve.</p><p><b>METHODS</b>Sixteen volunteers (9 males and 7 females) and 132 surgically confirmed patients with parotid tumors locating in the deep or shallow lobe of the parotid gland (including 89 with benign and 43 with malignant tumors) underwent MRI using T1WI and T2WI. The transverse images were obtained with the plane tilted 35 degrees to the foot, and the coronal images were acquired using conventional scanning.</p><p><b>RESULTS</b>On transverse T1WI, the parotid gland segments of the facial nerve displayed low signal with arc-shaped curve in the cross-section, showing a symmetrical dot-like low signal in the coronal plane. The facial nerve in 63% of the patients with parotid tumors in the cross-section could be displayed, but in the coronal plane the proportion reached 83%. MRI could accurately reveal the position of the parotid tumors in the deep or shallow lobe of the parotid gland.</p><p><b>CONCLUSION</b>MRI can show the major portion of the parotid gland segments of the facial nerve and has important value in locating the parotid tumors and displaying the relationship between the tumor and facial nerve.</p>

Adenovirus mediated gene transfer of tyrosinase gene on HepG2 cell by magnetic resonance imaging / 中国医学科学院学报

<p><b>OBJECTIVE</b>To evaluate the transfect results of recombinant adenovirus vector carrying tyrosinase gene (Ad-tyr) in vitro by magnetic resonance imaging (MRI) after the Ad-tyr was transfected into HepG2 cell.</p><p><b>METHODS</b>The Ad-tyr which carried the full-length cDNA of tyrosinase gene was transfected into HepG2 cell. The transfected cells were scan by MRI sequences of T1 weighted image (T1WI) , T2 weighted image (T2WI) , and short time inversion recovery (STIR) to observe the MRI signals of expressed melanin. Masson-Fontana staining was performed to search for melanin granules in transfected cells. Real-time PCR method was used to search for cDNA of tyrosinase gene.</p><p><b>RESULTS</b>Ad-tyr was transfected into HepG2 cells and synthesized a large amount of melanin inside. The synthesized melanin of 1 x 10(6) cells which had been transfected by Ad-tyr with the 50, 150, and 300 multiplicity of infection separately were all sufficient to be detected by MRI and showed high signals in MRI T1WI, T2WI, and STIR sequences. The signal intensities of MRI were positively correlated to the amounts of transfected Ad-tyr. The melanin granules were found in HepG2 cells in Masson-Fontana staining. The cDNA amount of tyrosinase gene in transfected HepG2 cells, which was detected by real-time PCR, was remarkably higher than that in nontransfected cells.</p><p><b>CONCLUSION</b>The synthesized melanin of HepG2 cells, which controlled by expression of exogenous gene, can be detected by MRI, indicating that the adenovirus vector can efficiently carry the tyrosinase gene into HepG2 cells.</p>