Three-Dimensional Magnetic Resonance Imaging Fast Field Echo Resembling a Computed Tomography Using Restricted Echo-Spacing Sequence Is Equivalent to 3-Dimensional Computed Tomography in Quantifying Bone Loss and Measuring Shoulder Morphology in Patients With Shoulder Dislocation.

PURPOSE: To evaluate the equivalence of 3-dimensional (3D) magnetic resonance imaging (MRI) (FRACTURE [Fast field echo Resembling A CT Using Restricted Echo-spacing]) and 3D computed tomography (CT) in quantifying bone loss in patients with shoulder dislocation and measuring morphologic parameters of the shoulder. METHODS: From July 2022 to June 2023, patients with anterior shoulder dislocation who were aged 18 years or older and underwent both MRI and CT within 1 week were included in the study. The MRI protocol included an additional FRACTURE sequence. Three-dimensional reconstructions of MRI (FRACTURE) and CT were completed by 2 independent observers using Mimics software (version 21.0) through simple threshold-based segmentation. For bone defect cases, 2 independent observers evaluated glenoid defect, percentage of glenoid defect, glenoid track, Hill-Sachs interval, and on-track/off-track. For all cases, glenoid width, glenoid height, humeral head-fitting sphere radius, critical shoulder angle, glenoid version, vault depth, and post-processing time were assessed. The paired t test was used to assess the differences between 3D CT and 3D MRI (FRACTURE). Bland-Altman plots were constructed to evaluate the consistency between 3D CT and 3D MRI (FRACTURE). Interobserver and intraobserver agreement was evaluated with the interclass correlation coefficient. The paired χ2 test and Cohen κ statistic were used for binary variables (on-track/off-track). RESULTS: A total of 56 patients (16 with bipolar bone defect, 5 with only Hill-Sachs lesion, and 35 without bone defect) were ultimately enrolled in the study. The measurements of 21 bone defect cases showed no statistically significant differences between 3D CT and 3D MRI: glenoid defect, 4.05 ± 1.44 mm with 3D CT versus 4.16 ± 1.39 mm with 3D MRI (P = .208); percentage of glenoid defect, 16.21% ± 5.95% versus 16.61% ± 5.66% (P = .199); glenoid track, 18.02 ± 2.97 mm versus 18.08 ± 2.98 mm (P = .659); and Hill-Sachs interval, 14.29 ± 1.93 mm versus 14.35 ± 2.07 mm (P = .668). No significant difference was found between 3D CT and 3D MRI in the diagnosis of on-track/off-track (P > .999), and diagnostic agreement was perfect (κ = 1.00, P < .001). There were no statistically significant differences between the 2 examination methods in the measurements of all 56 cases, except that the post-processing time of 3D MRI was significantly longer than that of 3D CT: glenoid height, 34.56 ± 1.98 mm with 3D CT versus 34.67 ± 2.01 mm with 3D MRI (P = .139); glenoid width, 25.32 ± 1.48 mm versus 25.45 ± 1.47 mm (P = .113); humeral head-fitting sphere radius, 22.91 ± 1.70 mm versus 23.00 ± 1.76 mm (P = .211); critical shoulder angle, 33.49° ± 2.55° versus 33.57° ± 2.51° (P = .328); glenoid version, -3.25° ± 2.57° versus -3.18° ± 2.57° (P = .322); vault depth, 37.43 ± 1.68 mm versus 37.58 ± 1.75 mm (P = .164); and post-processing time, 89.66 ± 10.20 seconds versus 360.93 ± 26.76 seconds (P < .001). For all assessments, the Bland-Altman plots showed excellent consistency between the 2 examination methods, and the interclass correlation coefficients revealed excellent interobserver and intraobserver agreement. CONCLUSIONS: Three-dimensional MRI (FRACTURE) is equivalent to 3D CT in quantifying bone loss in patients with shoulder dislocation and measuring shoulder morphologic parameters. LEVEL OF EVIDENCE: Level II, development of diagnostic criteria (consecutive patients with consistently applied reference standard and blinding).

Neutrophil-to-Lymphocyte Ratio Is Associated With Circumferential Wall Enhancement of Unruptured Intracranial Aneurysm.

Background and Purpose: Neutrophil-lymphocyte ratio (NLR) predicts clinical outcomes in patients with stroke. Aneurysm wall enhancement (AWE) on high-resolution vessel wall magnetic resonance imaging (HR-VWI) is an inflammation marker for intracranial aneurysm (IA). This study aims to evaluate the association of NLR as a peripheral blood inflammatory marker with circumferential AWE in patients with IA. Methods: We analyzed data of consecutive patients harboring IAs between September 2017 and December 2021 at our institution. The peripheral blood inflammatory indicators were compared between patients with ruptured and unruptured IAs. The presence of circumferential AWE in unruptured IA was identified and quantitatively measured using the aneurysm-to-pituitary stalk contrast ratio (CRstalk) on HR-VWI. We used the optimal cutoff value of 0.5 for CRstalk to differentiate circumferential AWE in unruptured IAs. We assessed the relationship of clinical, laboratory, and radiological characteristics with circumferential AWE and CRstalk ≥0.5 in unruptured IAs. Results: The study group was composed of one hundred and twenty-five patients with 142 IAs. NLR level at admission was significantly higher in patients with ruptured IAs than those with unruptured IAs (7.55 vs. 1.81; P < 0.001). AWE on HR-VWI was present in 30 patients with unruptured IAs (38.5%), including 12 with focal AWE and 18 with circumferential AWE. NLR (odds ratio (OR), 2.168; 95% CI, 1.149-4.088) and size (odds ratio, 1.370; 95% CI, 1.126-1.667) were independently associated with circumferential AWE in unruptured IA. NLR was also independently associated with circumferential AWE in small unruptured IA (<7 mm). Furthermore, NLR level at admission was associated with CRstalk ≥.5 in patients with unruptured IA. The optimal cutoff value of NLR for circumferential AWE was 1.86. Conclusion: NLR is a valuable peripheral blood inflammatory marker is more often in the rupture status of IA and was associated with circumferential AWE on HR-VWI in unruptured IA.

Circumferential wall enhancement with contrast ratio measurement in unruptured intracranial aneurysm for aneurysm instability.

BACKGROUND: Aneurysm wall enhancement on high-resolution vessel wall imaging (HR-VWI) may represent vessel wall inflammation for unruptured intracranial aneurysms (UIAs). Further evidence for the role of circumferential aneurysm wall enhancement (CAWE) in evaluating the instability of UIAs is required, especially in small aneurysms (<7 mm). METHODS: We analyzed patients with saccular UIAs who prospectively underwent HR-VWI on a 3.0 T MRI scanner in our center from September 2017 to August 2021. The presence of AWE was identified and quantitatively measured using the aneurysm-to-pituitary stalk contrast ratio (CRstalk) with maximal signal intensity value. The PHASES and ELAPSS scores were used to assess the risk of aneurysm rupture and growth. We evaluated the association of CAWE and CRstalk value with intracranial aneurysm instability. RESULTS: One hundred patients with 109 saccular UIAs were included in this study. Eighty-three UIAs (76.1%) had a size smaller than 7 mm. PHASES and ELAPSS scores were significantly higher in UIAs with CAWE than in UIAs without CAWE (p < .01). The association of CAWE with PHASES and ELAPSS scores remained in small UIAs (<7 mm). The optimal cutoff value of CRstalk for CAWE was 0.5. PHASES and ELAPSS scores were significantly higher in UIAs with CRstalk ≥0.5 than in UIAs with CRstalk <0.5 (p < .01). CONCLUSIONS: CAWE on HR-VWI is a valuable imaging marker for aneurysm instability in UIAs. CRstalk value ≥0.5 may be associated with a higher risk of intracranial aneurysm rupture and growth.

[Adenovirus mediated gene transfer of tyrosinase gene on HepG2 cell by magnetic resonance imaging].

OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

[Diffusion weighted imaging features of normal uterine cervix and cervical carcinoma].

BACKGROUND & OBJECTIVE: Magnetic resonance imaging (MRI) is a feasible method to detect, diagnose and stage cervical cancer. This study was to analyze the diffusion weighted imaging (DWI) features of normal uterine cervix and cervical carcinoma, and assess the values of DWI in diagnosis and monitor of cervical carcinoma after radiotherapy. METHODS: Routine MRI sequence and axial diffusion weighted sequence (b=800 s/mm2) were performed in 20 patients with cervical carcinoma and in 16 healthy women as control. The apparent diffusion coefficient (ADC) values of normal uterine cervix and cervical carcinoma were compared. The ADC values of 7 cervical carcinoma patients before and after radiotherapy were compared. RESULTS: Normal uterine cervix presented 3 layers in DWI. The ADC value was significantly higher in normal uterine cervix than in cervical carcinoma [(1.71+/-0.14) x 10-3 mm2/s vs. (0.97+/-0.13) x 10(-3) mm2/s, P<0.01]. The ADC value of cervical carcinoma after radiotherapy was higher than that before radiotherapy [(1.49+/-1.40) x 10(-3) mm2/s vs. (1.02+/-0.06) x 10(-3) mm2/s], but was still lower than that of normal uterine cervix. CONCLUSION: DWI could be used to distinguish cervical carcinoma from normal uterine cervix, evaluate the extension of cervical carcinoma before therapy, and monitor the treatment response of cervical carcinoma after radiotherapy.

[Clinical significance of diffusion-weighted MRI with STIR-EPI in differential diagnosis of cervical lymph nodes].

OBJECTIVE: To evaluate the feasibility and efficacy of a new MRI imaging method--diffusion weighted imaging (DWI) with short TI version recovery-echo planar imaging (STIR-EPI) sequence in differentiating benign cervical lymph nodes from malignant ones. METHODS Twenty nasopharyngeal carcinoma patients and fourteen volunteers received both conventional MRI and DWI with STIR-EPI. Ability of detecting lymph nodes between conventional MRI and STIR-EPI-DWI was compared, and the difference of apparent diffusion coefficient (ADC) value between metastatic lymph node and normal lymph node was analyzed. RESULTS: DWI was more sensitive in detecting lymph node than conventional MRI. ADC value of metastatic lymph node (0. 766 +/- 0. 119) x 10 (-3) mm(2)/s was significantly lower than that of normal lymph node (0. 975 +/- 0. 179) x 10 - mm2/s (P < 0. 01). CONCLUSION: As a new MRI imaging technique in detecting cervical lymph nodes, diffusion weighted imaging ( DWI) with short TI version recovery-echo planar imaging ( STIR-EPI) sequence is more reliable and sensitive than conventional MRI imaging, providing an alternative way to differentiate benign lymph nodes from malignant ones.

[MRI performance and diagnosis of schwannomas from cranial nerves in posterior cranial fossae].

BACKGROUND & OBJECTIVE: Cranial nerve schwannomas originate frequently in posterior cranial fossae and have various and complex MRI performances, some of which are still not well known. This study was to explore MRI performances and features of schwannomas from cranial nerves in posterior cranial fossae. METHODS: The MRI performances of 75 cases of schwannoma from cranial nerves in posterior cranial fossae, including trigeminal (n=9), facial (n=1), acoustic (n=53), 9th-11th (n=9) and hypoglossal (n=3) schwannomas, confirmed by surgical and pathologic findings, were analyzed retrospectively. RESULTS: Most of schwannomas in posterior cranial fossae were solid-cystic lesions when their sizes were larger than 1.5 cm in diameter. Small lesions (less than 1.5 cm in diameter) may be completely solid, which were closely related to cranial nerves. On T1WI, the solid part of tumor appeared iso- or slightly hypointense, while cystic part was hypointense. On T2WI, solid part appeared high or slightly high signal intensity, but cystic part appeared very high signal intensity. On contrast-enhanced T1WI, there was obvious enhancement in the solid part, but not in the cystic part. Some typical signs were very useful to infer tumor origin, such as, dumbbell-shaped trigeminal schwannoma extended across the middle and posterior cranial fossa, enlargement of internal auditory canal, widened jugular foramen and hypoglossal foramen caused by acoustic schwannoma, the 9th-11th shcwannoma, and hypoglossal schwannoma, respectively. The correct ratio for qualitative diagnosis of schwannoma was 92% using MRI, but the incorrect ratio for identifying the nerve of tumor origin was 8.7%. CONCLUSION: MRI is a good method in qualitative diagnosis of schwannoma and identifying cranial nerves of tumor origin in posterior cranial fossae.

[Three-dimensional reconstruction and image fusion between liver focal lesions and dynamic contrast-enhanced magnetic resonance angiography].

BACKGROUND & OBJECTIVES: Identifying the correlation of focal lesions to the liver vessel system is a key factor in selecting treatment patterns for focal hepatic diseases. This study was to evaluate the feasibility of 3-dimensional reconstruction and the fusion image between the 3-dimensional dynamic contrast-enhanced magnetic resonance angiography (3D DCE MRA) and the focal hepatic lesions, and further, explore the clinical application of this method. METHODS: 3D DCE-MRA and conventional magnetic resonance imaging (MRI) were performed. The angiography and focal hepatic lesions were reconstructed with maximum intensity projection (MIP) and surface shaded display (SSD), and then fused together. Of the 25 cases with evaluable images, 2 were hemangioma, 3 were focal nodular hyperplasia, 1 was hepatocellular adenoma, 2 were macroregenerative nodule, 2 were hepatobiliary cystadenocarcinoma, and 17 were hepatocellular carcinoma; 21 were confirmed by operation resection, and 4 received digital subtraction angiography (DSA). RESULTS: The anatomic relationship between the lesions and the vessels were well shown. Of the 27 cases, 5 showed normal vessel branching, 6 showed feeding arteries from the hepatic artery, 11 showed compressed and shifted trunks of the vessels, 6 showed tumor invaded vessels, and 11 showed the tumor embolism in the portal vein or the inferior vena cave; 9 also showed MRI signs of portal hypertension. MIP was prior to SSD in demonstrating small branches of the hepatic vessels. CONCLUSION: The 3-dimensional reconstruction and fusion images between 3D DCE-MRA and the focal hepatic lesions by using MIP and SSD can easily display the anatomic relationship between the focal hepatic lesions and the hepatic vessels, and thus can help the surgeons to localize lesions, minimize operating time and decide the extent of surgical resection.

[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.

[Types of liver metastases on MR imaging and characteristics of uncommon types].

BACKGROUND & OBJECTIVE: Although liver metastases are very common, some of them would be misdiagnosed because of their specific appearance on imaging. This study was to summarize the types of liver metastases according to the magnetic resonance imaging (MRI) appearance, and explore the characteristics of uncommon types to improve the accuracy of diagnosis. METHODS: A total of 174 consecutive patients with liver metastases were screened from the patients with diagnosis or suspicion of liver metastases according to plate or enhanced MRI scan. Liver metastases were confirmed through pathologic examination, medical imaging, or follow-up. Lesions were categorized as nodular, segment, and diffusion classes by shape, and categorized as common, mimicking hemangioma, and mimicking cyst patterns according to the characteristics of signal intensity. RESULTS: Common primary tumors of liver metastases were colon and rectum carcinomas (31.0%). According to the shape of lesions, the proportions of nodular, segment, and diffusion classes were 96.6%, 2.3%, and 1.1%, respectively. According to the characteristics of signal intensity, the proportions of common, mimicking hemangioma, and mimicking cyst patterns were 87.9%, 4.0%, and 8.1%, respectively. CONCLUSIONS: Most liver metastases are nodular in shape, and present as common pattern, but some uncommon types also exist. MRI scan and clinical follow-up could increase the accuracy of diagnosis.

[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.

[Correlation of MR imaging features and histopathology of synovial sarcoma].

BACKGROUND & OBJECTIVE: Magnetic resonance imaging (MRI) is the best detective technique for soft tissue tumors, but it lacks specific imaging signs to distinguish various tumors. The synovial sarcoma is observed more frequently in soft tissue tumors. This study was to evaluate correlation of MRI features and histopathology of synovial sarcoma, and to improve the diagnostic accuracy of synovial sarcoma by MRI. METHODS: Twelve patients with synovial sarcomas were confirmed by operation and histopathology, included 9 men, and 3 women, aged from 35 to 50 years. Ten tumors located in lower limbs, 2 located in upper limbs. MRI was performed with a 0.5T magnet system. All images were obtained through T1-weighted imaging (T(1)WI), and T(2)-weighted imaging (T(2)WI), and some images were obtained by T(2)WI with stair. All patients received enhanced scan after Gd-DTPA injection. Radiological and histopathologic findings were compared. RESULTS: All tumors located in the places closed to joints, 2 invaded into joints, 3 invaded into bones. On T(1)WI, 12 tumors displayed signal intensity similar to that of skeletal muscle, and 3 showed cystic high intensity areas similar to that of subcutaneous fat. On T(2)WI, 6 tumors showed hyper-, iso-, and hypointense areas relative to fat constituting a triple signal intensity; 6 were multilocular, 3 were irregular, 3 were circular or elliptical. The septa configurations were seen in 5 tumors, fluid-fluid level sign was seen in 1 tumor. Maximum diameters of tumors ranged from 3 to 13 cm. All tumors enhanced asymmetrically after Gd-DTPA injection. On histological examination, 7 were poorly differentiated monophasic type, 3 were well differentiated monophasic type, 2 were biphasic type, 6 had old and/or fresh hemorrhage, 5 had large necrosis areas, 2 had calcification. CONCLUSION: MRI manifestation is specific in synovial sarcoma, and may be correlated with histopathology of synovial sarcoma.

[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.

[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.