[Value of Radiation Therapy Oncology Group guidelines based on MR imaging in diagnosing lymph node metastasis of nasopharyngeal carcinoma].

BACKGROUND AND OBJECTIVE: Radiation Therapy Oncology Group (RTOG) and other major cooperative groups endorse the consensus guidelines for the delineation of the node levels in stage N0 cases. But it is unclear if these guidelines can be extrapolated to N+ cases. This study was to explore the value of RTOG guidelines in delineating cervical target volumes for nasopharyngeal carcinoma (NPC) patients with lymph node metastasis. METHODS: Conventional magnetic resonance imaging (MRI) of the nasopharynx, including plain and contrast enhanced sequences, was performed on 254 naive NPC patients. The lymph nodes were divided into six cervical levels plus retropharyngeal nodes (RN) according to RTOG guidelines proposed in 2003. RESULTS: Anatomic boundaries of node levels were observed clearly on MRI. Of the 254 patients, 107 (42.1%) had obvious lymph node necrosis, 78 (30.7%) had extracapsular nodal spread, four (1.6%) had skipped metastasis. The levels of lymph node metastases in 51 (20.1%) patients were beyond RTOG guidelines, 42 of which were above cranial level IIb, six were behind the anterior edge of the trapezius muscle, and 23 were below the caudal of level IV; 20 patients had two regions of lymph node metastases beyond RTOG guidelines. No patient only with lymph node metastasis beyond RTOG guidelines was found. CONCLUSIONS: MRI is feasible to diagnose cervical node metastasis with RTOG guidelines. The boundaries of node levels should be enlarged rationally when delineating target volumes for the N+ NPC patients according to RTOG guidelines.

[Value of multi-slice spiral CT with three-dimensional reconstruction in the diagnosis of neoplastic lesions in the jawbones].

OBJECTIVE: To assess the value of multi-slice spiral CT (MSCT) with three dimensional (3D) reconstruction in the diagnosis of neoplastic lesions in the jawbones. METHODS: Thirty-three patients with neoplastic lesions of the jawbones underwent MSCT scanning with 3D reconstruction. Of these patients, 14 had ameloblastoma, 8 had hemangioma, 3 had osteosarcoma, 3 had ossifying fibroma, 2 had chondrosarcoma, 2 had fibrosarcoma, and 1 had odontogenic myxoma. Preoperative MSCT scanning was performed with the slice thickness of 2 mm, and 3D reconstruction of the images was conducted by means of multi-planar reconstruction (MPR), curved-planar reformation (CRP), and 3D volume rendering technique (VRT). The results were compared with those observed during the operations. RESULTS: In the 33 cases, the neoplastic lesions of the jawbones were displayed by 2D or 3D imaging and confirmed by intraoperative findings. Two-dimensional imaging allowed better observation than 3D imaging of the deep structures, whereas 3D imaging was superior in visualizing the morphological changes of the compromised bones and the spatial relationship between the tumors and surrounding structures. Two-dimensional imaging and MPR were excellent in revealing the internal structures and pathological changes of tumors, having also better performance in showing the tumors involving the soft tissues. Benign tumors were most visualized as bone expansion changes with well defined ovoid or lobulated borderlines, and malignant ones often resulted in adjacent bony destruction and soft tissue masses. CONCLUSION: MSCT examination is useful in defining the scope of tumor involvement and bony changes to help in the definite diagnosis, differential diagnosis and choice of clinical treatment. Two-dimensional imaging, MPR, VRT and CRP have their respective advantages and limitations in showing jawbone tumor, and their combination can be of great clinical value.

[Preliminary application of functional magnetic resonance imaging to neurosurgery].

BACKGROUND & OBJECTIVE: Motor functional deficit may be caused by surgery resection of brain tumors around the central sulcus. This study was to evaluate the application of functional magnetic resonance imaging (fMRI) to neurosurgery through identifying motor hand functional cortex and depicting the relationship between the cortex and tumor with fMRI before surgery. METHODS: Routine MRI and fMRI were performed on 31 patients with brain tumor around the central sulcus. Of the 31 cases of brain tumor, 10 were metastases, 11 were gliomas, 6 were meningiomas, 2 were arterial-venal malformation (AVM), and 2 were arachnoid cysts. fMRI was performed using FFE-EPI sequence. Sixteen continuent slices with 4 mm thickness and 0 gap parallel to bicommissural line were scanned during the rest, and actions of opening and closing of hand were imaged. A total of 1,280 functional original pictures and statistical Z-score maps were obtained. RESULTS: The activation areas of motor hand functional cortex were showed in all patients except 2 whose heads moved obviously during the scanning. The minimal distance between the functional cortex and tumor was measured. There were 3 types of activation of motor hand functimal cortex, including activation spots in or near the tumor, deformation and shift of cortex activation area, normal shape and location of cortex activation area. Other activation areas in different places of brain in individual patients were also appeared. CONCLUSION: fMRI may help to identify the relationship between the brain tumors near central sulcus and the location of motor hand functional cortex, therefore, provide reference for neurosurgery.

[Significance of dynamic enhanced MRI in differential diagnosis of radiofibrosis and recurrent nasopharyngeal carcinoma at the basilar clivus].

BACKGROUND & OBJECTIVE: Basilar clivus is a common site of recurrent nasopharyngeal carcinoma (RNPC). Biopsy of the basilar clivus is seldom done because of its deep location and complex anatomic structure, therefore, early differential diagnosis of radiofibrosis (RF) and RNPC at the basilar clivus is very difficult. This study was designed to investigate the characteristics of radiofibrosis and RNPC at the basilar clivus on dynamic enhanced magnetic resonance imaging (DMRI) for differential diagnosis. METHODS: A total of 38 NPC patients, treated in Cancer Center and the Second Affiliated Hospital of Sun Yat-sen University with follow-up of 1-5 years, were divided into 2 groups: 22 in RF group and 16 in RNPC (RNPC at the basilar clivus) group. After conventional plain MRI scan of nasopharynx, DMRI and conventional contrast enhanced T(1)-weighted imaging (T1WI) were performed. Maximal contrast enhancement ratio (MCER), time to MCER (Tmax), and contrast enhancement ratio at the 40th second of DMRI (CER(40s)) of basilar clivus, condylar process, and nasal concha were measured. RESULTS: The MCER and CER(40s) of RF at the basilar clivus were lower, and the Tmax was longer than those of RNPC at the basilar clivus. When CER40s > or =150%, CER40s of basilar clivus > or = CER(40s) of nasal concha, and the combination of these 2 indexes were respectively set as the DMRI diagnostic criteria of RNPC at the basilar clivus, the diagnostic sensitivity of the second criterion was the highest (81.3%), and the diagnostic specificity of the third criterion was also the highest (86.4%). CONCLUSIONS: DMRI is helpful for differential diagnosis of radiofibrosis and RNPC at the basilar clivus. RNPC at the basilar clivus is highly suggested when it meet the criteria of both CER(40s) > or =150% and CER(40s) of basilar clivus > or = CER(40s) of nasal concha. When the 2 criteria are conflictive, the latter is more accurate, MCER and Tmax of the basilar clivus should be took into consideration.

[Magnetic resonance imaging manifestations of radiation injury in brain stem and cervical spinal cord of nasopharyngeal carcinoma patients after radiotherapy].

BACKGROUND & OBJECTIVE: It is very important to diagnose the radiation injury in brain stem and cervical spinal cord of patients with nasopharyngeal carcinoma (NPC) after radiotherapy. Magnetic resonance imaging (MRI) manifestations of radiation encephalopathy have been widely reported, while those of radiation injury in brain stem and cervical spinal cord have been seldom reported. This study was to analyze the MRI characteristics of radiation injury in brain stem and cervical spinal cord of patients with NPC after radiotherapy. METHODS: MRI was performed in 60 NPC patients 6 months to 5 years after radiotherapy. The imaging sequences included T(1)-weighted image (T(1)WI), T2-weighted image (T(2)WI), fluid attenuated inversion recovery (FLAIR). All patients received T(1)WI contrast-enhanced scanning. RESULTS: Of the 60 patients, 6 had lesions in cervical spinal cord, 54 had lesions in brain stem. Of the 54 cases of radiation injury in brain stem, most lesions located in pons (20 cases), basis pons and medulla oblongata (26 cases), others located in mesencephalon (3 cases), medulla oblongata (5 cases). All lesions showed hypo- or iso-intense signal on T(1)WI, and hyper-intense signal on T(2)WI. After contrast-enhanced scanning, 11 cases (18.3%) had no enhancement; 49 (81.7%) markedly enhanced with 21 cases (42.9%) of homogenous patchy enhancement, and 28 cases (57.1%) of hetergenerous ringed and patchy enhancement. CONCLUSION: MRI shows clearly the radiation injury in brain stem and cervical spinal cord of NPC patients after radiotherapy.

[Magnetic resonance imaging diagnosis of cervical lymph node metastasis from lingual squamous cell carcinoma].

BACKGROUND & OBJECTIVE: The identification of cervical lymph node metastasis is very important for the treatment and prognosis prediction of lingual squamous cell carcinoma. Simple palpation is unsatisfactory for the accurate diagnosis of cervical lymph node metastasis. Magnetic resonance imaging (MRI) has been increasingly used to evaluate cervical lymph node status. This study was to explore MRI features of cervical lymph nodes metastasis from lingual squamous cell carcinoma, and to investigate the role of MRI in diagnosing this kind of metastasis. METHODS: The MR images of 448 nodal levels in 92 patients with lingual squamous cell carcinoma were analyzed, and compared with their pathologic diagnoses. RESULTS: Of the 488 nodal levels, 166 (37.1%) were proved pathologically as metastases, level II was the most commonly involved. False-positive and false-negative rates of MRI diagnoses were higher in levels I, and II than in levels III, IV, and V. There is no statistical difference in the incidence of cervical lymph nodes metastases of different nodal levels between squamous cell carcinoma of corpus linguae and that of radix linguae. Obvious central nodal necrosis was seen in 76 nodal levels at MR images,which were proved pathologically as metastatic nodes. Extracapsular nodal invasions in 34 nodal levels had irregular contour, and infiltration of adjacent fat tissues around lymph nodes, among which carotid artery walls were encased in 2 cases. With the diagnostic criteria of metastasis as the minimal nodal diameter of >/= 8 mm or central nodal necrosis, the diagnostic sensitivity, specificity, and accuracy of MRI were 79.5%, 90.4%, and 86.4%, respectively. CONCLUSIONS: The incidence of cervical lymph nodes metastasis from lingual squamous cell carcinoma is highest in level II. MRI diagnostic criteria of cervical lymph nodes metastasis are nodal size, central nodal necrosis, and irregular contour of lymph nodes. MRI may diagnose lymph node metastasis in levels III-V with high accuracy, While its diagnosis accuracy on levels I-II is affected by the sites, which weakens its clinical value.

[MRI performance and diagnosis of meningioma--a report of 126 cases].

BACKGROUND & OBJECTIVE: In MRI study of meningioma, it was lack of large group of patients to evaluate MRI qualitative diagnosis, and no consensus had been achieved concerning problems such as peritumoral edema in meningioma. This study was to summarize main clues for diagnosing meningioma through analyzing MRI performance of 126 patients with meningioma. METHODS: Among 126 patients with meningioma, 32 were syncytial, 35 were fibroblastic, 24 were psammomatous, 9 were angioblastic, 18 were transitional, 3 were papillary, and 5 were malignant. All patients were scanned with T1, T2-weighted imaging (T1WI, T2WI), and contrast-enhanced T1WI. RESULTS: Convexity of brain was more likely to be involved, among 126 cases of meningioma, 45 (35.7%) tumors located at convexity of brain. The size of tumor ranged from 1.4 to 9.9 cm. Eighty-one percent of tumors were round or oval in shape. Isointensity or slight hyperintensity of T2WI signals detected in 70.6% patients. The rates of tail sign, and pseudo-capsule were 62.7%, and 49.2%. Extruding sign of brain parenchyma was observed in 83.8% (57/68)of patients with tumor size of > 4 cm. Significantly even and increasing sign in contrast-enhanced T1WI were observed in 104 patients (82.5%). Peritumoral edema occurred in 57 patients (45.1%), and related to tumor size. Other rare signs included cystic changes, bleeding, calcification, osteal changes, and introtumoral vessel symptoms. The correct rate of diagnosis was 95.2%. CONCLUSIONS: MRI performances of meningioma are various. Judgment of extra-brain tumor, typical T2WI signals, tail sign, and significantly even and increasing sign are key factors for diagnosing meningioma.

[Diagnostic value of MR diffusion tensor imaging on radiation-induced early brain injury of nasopharyngeal carcinoma after radiotherapy].

BACKGROUND & OBJECTIVE: MR diffusion tensor imaging (DTI), a new MRI technique, can observe water molecule diffusion non-invasively at molecular level. This study was to assess diagnostic value of DTI on post-radiotherapy brain injury by quantitatively analyzing diffuse features of water in bilateral temporal lobes alba of those nasopharyngeal carcinoma (NPC) patients with normal conventional MRI performances. METHODS: DTI was performed in 13 NPC patients with normal conventional MRI performances after radiotherapy, and 21 healthy controls. Isotropic apparent diffusion coefficient (ADCiso) and anisotropic index (AI) were measured in bilateral temporal lobes alba. RESULTS: ADCiso of patient group was (631.30+/-27.83) x 10(-6) mm2/s, while that of control group was (651.76+/-39.10) x 10(-6) mm2/s (P>0.05). Temporal lobes diffusion AI decreased significantly in patient group, mean fractional anisotropy (FA) was 0.405+/-0.042, mean relative anisotropy (RA) was 0.355+/-0.044, and mean 1 minus volume ratio (1-VR) was 0.192+/-0.042; while those in control group were 0.463+/-0.047, 0.418+/-0.052, and 0.257+/-0.055, respectively (P< 0.01). CONCLUSIONS: DTI can early detect subtle alba changes in NPC patients after radiotherapy, which conventional MRI failed to sense. AI is more sensitive than ADCiso, may better describe the diffuse features of water molecules, and evaluate the temporal lobes alba changes before and after NPC radiotherapy.

[Diagnosis of thyroid carcinoma by magnetic resonance imaging (MRI)].

BACKGROUND & OBJECTIVE: Magnetic resonance imaging (MRI) has been demonstrated to be important for the evaluation of thyroid diseases. Several foreign authors have reported MRI manifestation of thyroid carcinoma; however, there were few reports about this in China. This study was designed to investigate the diagnostic value of MRI in thyroid carcinoma by comparing MRI manifestation with histopathological features of thyroid carcinoma. METHODS: Thirty-one cases of thyroid carcinoma were analyzed retrospectively with preoperational MRI and postoperational pathological findings. RESULTS: Among 31 cases of thyroid carcinoma, 20 cases showed heterogeneous intensity in MRI and liquefied or hemorrhagic or cystic degeneration at histopathological examination. Twenty-two cases showed ill defined. Twenty-two cases showed irregular shapes, of 10 cases showed "the discontinuous capsule-like sign with low signal intensity around the tumor" in MRI and that pseudocapsules have been penetrated and partially destroyed by tumors in histopathological findings. Nineteen cases showed the tumors infiltrated the adjacent structures. Nineteen cases showed metastatic lymphadenopathy on the neck. CONCLUSION: "The discontinuous capsule-like sign with low signal intensity around the tumor" is the characteristic manifestation of thyroid carcinoma on MRI. Heterogeneous signal, obscure margin, and irregular shape are the important features for diagnosis of thyroid carcinoma. MRI can demonstrate small lesions, provide the precise morphologic characteristics of lesions, and accurately define the local extension of tumors.

[Value of manifestations of magnetic resonance imaging (MRI) in diagnosis of parotid tumors and their pathological bases].

BACKGROUND & OBJECTIVE: The pathologic types of parotid tumor are very complicated and the advantage of magnetic resonance imaging (MRI) in diagnosis of these tumors is very obvious; however, there is not still accordance at several areas of MRI diagnosis of them. A large amount of cases are needed for analyzing these MRI features and their pathological fundament. This study was conducted to summarize the MRI manifestations of common benign and malignant tumors and to explore the value of the morphological features of MRI in histological diagnosis of parotid tumor. METHODS: The MRI manifestations for 132 cases(140 lesions) of parotid tumor/lesion were collected, including 89 benign tumors/lesions and 43 malignant tumors. Of them, 112 cases were proved by surgery, 17 cases by biopsy, and 3 cases by clinic observation. MRI features were completely compared with pathological results of surgical samples slice by slice in 58 cases. T(1)WI and T(2)WI sequence were used in MRI unenhancement scan; 108 cases (115 lesions) were examined with both unenhancement and enhancement. Chi-square test was used for statistic analysis. RESULTS: (1) The MRI features of common parotid benign tumors were as following: 40 cases of Warthin's tumors enhanced slightly and more than half of them (25 cases) appeared low or equal signal intensity in T(2)WI; 22 cases of pleomorphic adenoma appeared high and unhomogeneous signal intensity in T(2)WI; 5 cases of hemangioma were characterized by their vascular structures which were enlarged than normal; 3 cases of lymphangioma not only appeared specially irregular shape but also surrounded adjacent structures of parotid gland (3 cases). The features of 4 cases of parotid lipoma were same as those in other position of the body.(2) The MRI features of common parotid malignant tumors were as following: 8 cases of malignant pleomorphic adenoma appeared high and unhomogeneous signals in T(2)WI together with irregular shape and ill-defined margin; 7 cases of adenoid cystic carcinoma characterized by invasion of very large range surrounding parotid gland. In 8 cases of malignant mucoepidermoid carcinoma, 3 cases showed low-grade malignant mucoepidermoid carcinomas, which had well-defined margin and were difficult to distinguish from benign tumor. However, 5 cases of high-grade malignant mucoepidermoid carcinoma showed ill-defined margin, their features were tend to undergo necrosis and invade lymph node; 9 cases of lymphomas were all secondary lesions and there were two characters in their imaging, one was the wide involved range, the other was they consisted of several nodes. The shapes of 3 cases acinic cell carcinoma could be either regular or irregular, the cystic areas could be found in them with high signal intensity both on T(1)WI and T(2)WI. CONCLUSION: There are certain characters for each of common benign and malignant parotid tumors in MRI and these may be helpful for histological diagnosis in most of them.

[Magnetic resonance imaging (MRI) in evaluation of tyrosinase gene expression in HepG2 cell].

BACKGROUND & OBJECTIVE: Gene therapy is the frontier of life science. There is no perfect method to evaluate gene expression without invasion at present. Medical imaging connecting with molecular biology might be helpful; however, the technology is just on the horizon. The authors conducted this study in vitro by transferring reporter tyrosinase gene into HepG2 cell to apply magnetic resonance imaging (MR) for evaluating gene expression. METHODS: The plasmid of pcDNA3tyr carried the full-length cDNA of tyrosinase gene was transfected into HepG2 cell by lipofectin, its property of synthesizing melanin was used to produce high signal in T1WI MR image and then to evaluate gene expression. Further identification were performed with searching melanin granules by Fontana staining and searching cDNA of tyrosinase gene using reverse transcription-polymerase chain reaction (RT-PCR). RESULTS: (1)The melanin granules were found in HepG2 cell using Fontana staining. (2)The cDNA fragment of tyrosinase gene was detectable in transferred HepG2 cell by RT-PCR. (3)Plasmid of pcDNA3tyr was transfected into HepG2 cell and synthesized a large amount of melanin in HepG2 cell; the synthetic melanin appeared high signal in T1WI MR imaging as same as natural melanin and was enough to be detected by MR. And further, the signal intensity was positively related to the amount of transferred plasmid. CONCLUSION: The fact that synthetic melanin of HepG2 cell can be detected by MR demonstrates that medical imaging connecting with molecular biology can be used to evaluate the result of gene expression in vitro.

[Relationship between computed tomography (CT) manifestations and pathology in thyroid carcinoma].

BACKGROUND & OBJECTIVE: In clinical diagnosis and treatment of thyroid carcinoma, the misdiagnosis rate is about 40%-70%and the recurrence is about 30%. This study was designed to investigate the relationship between the CT features of thyroid carcinoma and its clinical pathology. METHODS: Fourty-six cases of thyroid carcinoma, pathologically proven, were retrospectively analyzed for CT and histological findings. RESULTS: Of 46 patients with thyroid carcinoma, 31 cases showed heterogeneous density, 30 cases showed irregular shape, 37 cases showed untidy margin, 16 cases showed peninsular tubercles around the tumor,and 10 cases showed no complete enhanced ring around the tumor. 20 cases were detected calcifications, including 9 cases fine globular calcifications, 4 cases nodular calcifications, 7 cases mixture calcifications. In addition,"calcified nodule in cyst sign" were found in 7 cases. 23 cases infiltrated the adjacent structures and 15 cases were revealed metastatic lymphadenopathy on the neck. CONCLUSION: Some cases of thyroid carcinoma can be diagnosed correctly according to the characteristic manifestations on CT. Different pathological types of thyroid carcinoma were related to calcification manifestations and adjacent structure invasion. CT scan can provide reliable information in selecting therapeutic methods.

[Magnetic resonance imaging manifestation of 500 patients with primary hepatic cell carcinoma].

BACKGROUND & OBJECTIVE: Magnetic resonance imaging (MRI) is one of the main imaging diagnostic methods for primary hepatic cell carcinoma. This study was designed to summarize the MRI manifestation and to evaluate Gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA) and super paramagnetic iron oxide particles(SPIO) enhanced MRI in diagnosis of small hepatic carcinoma. MATERIALS & METHODS: Five hundreds patients diagnosed as primary hepatic cell carcinoma histologically were examined by MRI plain scan, plain scan + Gd-DTPA enhanced T1 weighted imaging, and plain scan + Gd-DTPA T1 weighted imaging + SPIO-enhanced heavy T2 weighted imaging was performed, respectively. RESULTS: In 500 patients, there were 65 (13.0%) small hepatic cell carcinoma, 81(16.2%) nodular lesions, 325 (65.0%) lump lesions; 29(5.8%) diffused lesions. 310(62%) patients were single lesion and the rest were multiple lesions. Twelve percent of the cases was associated with lymph nodes metastases, and 31.4% were complicated with vascular invasion. Diameter of the lesion was correlated positively to intro-hepatic metastases of the same or different lobe, the lymph nodes metastases and vascular invasion (P < 0.05). Totally 71 lesions were detected in the 65 cases with small hepatic carcinoma. Enhanced scan detected more lesions than plain scan (P < 0.05), and the lesions detected by Gd-DTPA + SPIO-enhanced scan were more than that by Gd-DTPA alone (P < 0.05). CONCLUSION: With the diameter of the lesion increase, the possibility of intro-hepatic metastases, lymph node metastases, and vascular invasion increased. For the MRI diagnosis of small HCC, enhanced scan especially Gd-DTPA + SPIO enhanced scan could detect more lesions than plain scan.