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BACKGROUND:Primates are considered to be the most appropriate animal model of lumbar intervertebraldisc degeneration, but the disc degenerated characteristics of monkeys were rarely reported. OBJECTIVE:To verify the degenerated regularity and characteristics of lumbar intervertebral disks in rhesus monkeys with magnetic resonance T2 mapping and T1ρimaging technology. METHODS:The sagittal lumbar intervertebral disc magnetic resonance T2 weighted imaging,T2 weighted mapping imaging and T1ρweighted imaging of 63 adult rhesus monkeys were acquired on 1.5T magnetic resonance equipment. The T2-map value and T1ρvalue of lumbar intervertebral disc regions of interest were calculated on the post-processing workstation. RESULTS AND CONCLUSION:(1) This study obtained 425 better magnetic resonance images of lumbar intervertebral disks in adult rhesus monkeys. T2-map value and T1ρvalue of nucleus pulposus were most consistent by different persons, and the Kappa coefficient was more than 0.93. (2) The T2-map value and T1ρvalue of nucleus pulposus were both negatively correlated significantly with Pfirrmann grades (r=-0.842, P<0.01;r=-0.896, P<0.01). The T1ρvalue and T2-map value of nucleus pulposus were significantly statistical y different between Pfirrmann grades I-IV (P<0.001, P<0.001). The T1ρvalue of nucleus pulposus was negatively correlated significantly with Pfirrmann grade II-III (r=-0.517, P<0.01) and Pfirrmann grade IV-V (r=-0.499, P<0.01). The T2-map value of nucleus pulposus was also negatively correlated significantly with Pfirrmann grade II-III (r=-0.617, P<0.01) and Pfirrmann grade IV-V (r=-0.652, P<0.01). (3) The T2-map value of L1-2 and L2-3 segments nucleus pulposus were significantly lower than that in L6-7 and L7-S1 segments (P<0.05). (4) There were significant differences in age among the T1ρvalue and T2-map value of nucleus pulposus (r=-0.702, P<0.001, r=-0.730, P<0.001). (5) It is concluded that magnetic resonance T2 mapping and T1ρimaging technology can objectively and sensitively assess the degenerated process of nucleus pulposus in rhesus monkeys. The degeneration in upper lumbar segments (L1-2 and L2-3) was earlier and more severe than that in lower lumbar segments (L6-7 and L7-S1) in rhesus monkeys. Age is one of the most important factors in lumbar intervertebral disc degeneration of adult rhesus monkeys.
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Objective To explore the diagnostic significance of CT and MRI in dermatofibrosarcoma protuberans.Methods Analyze the CT and MRI images of 16 cases which were confirmed as dermatofibrosarcoma protuberans by pathology.The medical imaging features of dermatofibrosarcoma protuberans were summarized.In the total 16 cases(including 6 male cases,10 female cases),15 cases had suffered from dermatofibrosarcoma protuberans for more than 1 year, 11 cases for more than 5 years, and 9 cases had history of recurrence.Results On MRI, the mass was slightly hypointense on T 1 WI, inhomogeneously hyperintense on T 2 WI with inhomogenous enhancement.The diameters of mass were less than 5 cm in 3 cases,and were more than 5cm in 13 cases.Fifteen cases had clear demarcation between the masses and their adjacent muscles , 7 cases had “suspension sign” in shapes, 10 cases had “sub-nodules outward” features at the edge of the tumors , 12 cases had “multinodular” features inside the tumor , and 8 tumors grew into the surrounding fat layer like roots.Conclusion Dermatofibrosarcoma protuberans can be diagnosed accurately based on the features displayed on CT and MRI.
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Objective To investigate the effect of imaging parameters and postprocessing methods on the quality of MR imaging of short T2 components with 3D ultrashort TE (UTE) double echo pulse sequence. Methods 3D UTE double echo pulse sequence was performed on dry human femoral specimen and the tibial diaphyses, knee joints, and tendons of ankles of a group of healthy volunteers. To investigate the effect of different trajectory delays of the imaging system(-6, -3, -2, - 1,0, 1,2, 3 s), different flip angles(4°, 8°, 12°, 16°, 20°, 24°), different TEs (0. 08, 0. 16, 0. 24, 0. 35 ms)and different postprocessing methods(difference imaging of subtracted volume and non-volume UTE)on the 3D UTE MR imaging quality, the SNR and CNR were calculated and compared, and the artifacts of the images were analysed. Results The cortical bone, periosteum, tendon and meniscus showed high signal intensity on the images of UTE pulse sequence. The best SNR was acquired with 2 s trajectory delay. The best flip angle was 8° to 12° for the human UTE imaging in vivo. The highest CNR was obtained from the TE of 0. 08 ms. The longer the TE was, the more artifacts appeared. The SNR of difference imagewas improved when image subtraction was performed afer multiplanar reconstruction (MPR) of the primary double echo images.Conclusions The short T2 components show high signal intensity on the MRI of 3D UTE double echo pulse sequence. The imaging quality can be improved by shortening TE, using appropriate flip angle and performing subtraction for difference image after MPR of the primary double echo images.
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Objective To assess the value of using MRI to evaluate the histopathological characteristic of limb soft-tissue aggressive fibromatosis (AF). Methods The MBI findings and histopathological data of 20 patients with AF were obtained and analyzed. The difference between the different signal regions in AF were compared of signal intensity in T1-weighted images, T2-weighted images and degree of enhancement. The data were processed with paired t test. The histopathology of different signal regions was observed in 6 cases on HE stain and Masson trichromic stain of AF specimen. Results (1) AF predominantly originated from the skeletal muscles (19/20), presenting as Iobulated mass with infiltrative growth(20/20) ;(2) A few claw-shaped neo-arteries(7/7) were delineated in the periphery of the mass in the 3D DCEMRA images as well as the mild tumor staining(7/7) ; (3) Based on the MRI findings, the porenchyma of 20 AF was divided into two distinct regions of structure: region Ⅰ and region Ⅱ. Region Ⅰ presented as hypointensity on both T1-weighted and T2-weighted images and no enhancement after i. v. administration of contrast. Region Ⅱ presented as mild hyperintensity on T2-weighted images and iso- or hypointensity on T1-weighted images and marked enhancement; (4) The signal intensity in T1-weighted images, T2-weighted images and degree of enhancement was 0. 10 ± 0. 02,0. 24 ± 0. 03, and ( 5.22 ± 0.42)% in region Ⅰ , respectively; and 0.79±0.04,3.05±0.08 and(151.5±8.61)% in region Ⅱ, respectively. The differences between region Ⅰ and region Ⅱ were statistically significant of signal intensity in T1-weighted images( t = 67. 37 ), and signal intensity in T2-weighted images( t = 196. 56) and degree of enhancement(t =76. 62) (P <0. 01 ) ; (5) Histologically, AF was composed of fibroblasts, fibrecytes and bundles of collagen fiber. On Massen triehromie stain, region Ⅰ was stained blue, being proven the mature collagen fibers. Region Ⅱ was predominantly composed of fibroblasts, fibrecytes and was not stained. Conclusion The region Ⅰ and region Ⅱ are the characteristic MRI manifestations of AF, and MBI precisely reflects the histopathological and biological feature of the tumor.
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nal surface coil,and it can be a promising method to diagnose interphalangeal joints lesions.
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ObjectiveTo study MRI features and pathologic basis of various periosteal changes in rabbit VX2 bone tumor and to evaluate the role of MRI in the change of periosteum in bone tumor. MethodsBone tumor models were induced by injection of VX2 carcinoma cell suspension into the medullary cavitv of right tibias in 32 rabbits.Thirty-six positive contrast cases and 4 negative contrast cases were established.Serial plain films and MRI examinations were performed at an interval of 5 days foliowing the implantation.Every 4 rabbits were sacrificed immediately after imaging. The findings of periosteal changes were compared between imaging features and pathologic Results . ResultsFrom the 5th to 15th day after implantation of VX2 carcinoma,periosteal edema was demonstrated in 32 tibias. On the 20th day,periosteal thickening Was revealed in 19 tibias. On the 25th day,periosteal new bone with the thickened periosteum attaching to its outer Surface was found in 12 tibias. On the 30th day,periosteal new bone with the thickened Deriosteum were elevated by the tumor in 11 tibias.On the 35th to 40th day,destruction of periosteal bone and periosteum were revealed.ConclusionsThe progress of periosteal changes in rabbit VX2 bone tumor included periosteal edema,periosteal thickening,periosteal new bone,destruction of periosteal new bone and destruction of periosteum. Various periosteal changes could be demonstrated on MRI and MRI is useful in evaluating periosteal changes.
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Objective To summarize the types and imaging features of periosteal anomaly in osteosarcoma.Further to seek the feature of genesis and advancement of periosteal anomaly and its clinical significance.Methods One hundred and twenty-eight patients with osteosarcoma were enrolled in this study,which consisted of 76 males and 52 females aging from 5 to 66 years old with an average of 19 years.Both x-ray plain film and MR images were obtained in all patients.and DWI were done in 23 patients.CT scanning was conducted in 48 patients.which included post-contrast scanning done in 36.The pathological gross specimen,macrosection and point-to-point microsection were obtained in each of 14 cases to correlate the imaging findings of periosteal anomaly to the pathological outcome.Results The imaging and pathological finding:(1)Periosteodema,occurring in 96 patients.The sign was merely demonstratable on MR image and presented as loosened periosteal structure with no tumoral infiltration pathologically.(2)Periosteal lift and thickening,demonstratable on both CT and MR image,including 13 noted on CT and 42 on MR image.Pathologically,non-tumoral infiltration was noted in the thickened periosteum.(3)Periosteal destruction,occurring in 48 patients.Periosteal destruction was merely demonstratable on MR image and presented as localized or generalized tumoral infiltration of the periosteum.(4)Linear periosteal neo-bone formation,demonstrated in 42 cases on plain films,13 cases on CT and 22 on MR images,respectively.The linear periosteal neo-bone formation was pathologically regularly arranged periosteal neo-bone.(5)Laminar periosteal neo-bone fomarion,demonstrated in 21 cases on plain films,6 cases on CT and 21 on MR images,respectively.Pathologically,it appeared as multi-layer arrangement.(6)Radiated and spiculate periosteal neo-bone formation,demonstrated in 13 cases on plain films,7 cases on CT and 14 on MR images,respectively.On both plain film and CT,the closer to the center of the tumor,the longer and denser the spicule was.The interspiculate structure was tumoral tissue pathologically.(7)Periosteal neo-bone formation of mixed type,demonstrated in 7 cases on plain films,4 cases on CT and 8 on MR images,respectively.It was composed of 2 types or more of periosteal neo-bone.Conclusions (1)Multiform periosteal anomaly can be induced by osteosarcoma,and difierent periosteal anomaly possesses different imaging findings and different pathological basis.(2)The pathologically-based classification of periosteal anomaly generalizes the 3-modality imaging findings of various periosteal pathological alterations.(3)MR imaging enables to demonstrate periosteal anomaly more early,and periosteodema and periosteal destruction without neo-bone formation can only be demonstrated by MR imaging.MR imaging is more sensitive than CT in displaying periosteal thickening.
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Objective To describe MR findings in inflammatory myofibroblastic tumor(IMT)of the soft tissue.Methods MR manifestations of 11 cases of IMT of the soft tissue were retrospectively analyzed,and the MR findings were correlated with surgical and histological results.Results The pathological classification of the tumors was type Ⅰ in 1 case,type Ⅱ in 4 cases.mainly type Ⅱ admixed with type Ⅰ in 3 cases,and mainly type Ⅱ admixed with type Ⅲ in 3 cases.In 4 cases with primary tumor,the tumors were spheroid in shape,with well-defined margin and pseudocapsule.In 2 cases with primary axillary tumor and 5 cases with recurrent tumor,the tumors were irregular in shape,with ill-defined margin and invasion of adjacent structures.The tumors were mainly isointensive in T1-weighted images.Tumors of different pathological classifications had different signal intensities in T2-weighted images:1 case of type Ⅰ tumor was bright:4 cases of type Ⅱ tumor and 3 cases of type Ⅱ tumor admixed with type Ⅰ tumor were slig}ltly bright;3 cases of type Ⅱ tumor admixed with type Ⅲ were isointense or slightly hypointense in signal.All of the 11 eases in the study exhibited"pitaya cross-section sign"in T2-weighted sequence,which referred to discrete punctuate foci of relatively hypointensity in the background of hyperintensity,slightly hypointensity or isointensity.All of the 11 cases exhibited inhomogeneously significant enhancement after gadolinium administration.In the follow-up of the 6 cases of primary tumor,4 cases had recurrence,1 case had no recurrence,and 1 ease was lost in the follow-up process.In the follow-up of the 5 cases of recurrent tumor,4 cases showed recurrence again,and 3 cases were lost in the follow-up process.Conclusions The IMT of the soft tissue has characteristic MR features.The signal intensity of the tumor on T2-weighted sequence could reflect the pathological type of the tumor to some extent."pitaya cross-section sign"could be a pathogenomic sign of the IMT of the soft tissue.
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Objective To investigate the application of 3D ultrashort TE double echo pulse sequence in the bone and joint MR imaging. Methods Eight volunteers and a porcine fibula in vitro with intact muscle were involved in this study. Among the volunteers, one was suspected with meniscus tear, the others were asypmtomatic. MR imaging of 3D ultrashort TE double echo pulse sequence were performed on the tibial diaphysis, knee joint, ankle and wrist of each volunteer and the porcine fibula in vitro. Using the first echo images subtract with the second echo images, we observed the subtracted images from the primary double echo images and MPR images respectively. We then compared the difference of SNR. Four different echo times of the first echo (TE1) in the images were set as 0. 08 ms, 0. 16 ms, 0. 24 ms, 0. 35 ms. The quality of the subtracted images from the primary double echo images of the four different TE1 was compared.The MIP images from the primary double echo images with TE1 of 0. 08ms were performed to display the 3D structure of the ankle tendons. The data were analysed with One-Way ANOVA and Paired-Samples t test statistically. Results The 3D images of the tendons were displayed through MIP of the subtracted images from the primary double echo images. The cortical bones, periosteums, tendons and menisci of the 8 volunteers appeared as high signal intensity in UTE pulse sequence. The SNR of the subtracted images from MPR images (SNR, 3.76 ± 0. 88) was significantly higher than those from the primary double echo images(SNR,2. 82±0. 75) (t = - 4. 851, P < 0. 01). There were significant differences among the subtracted images from each of the four different TE1. The highest quality were obtained from the TE1 of 0.08ms. The CNR were as follows: CNR<,0.08ms>1.74±0. 54, CNR<,0.16ms> 1.35 + 0. 60, CNR0.24ms>1.20±0. 48,CNR<0.35ms> 0.89±0. 24 (F = 3. 681, P < 0. 05). The artifacts appeared markedly with prolonging of the TE1.Conclusion The MRI of ultrashort TE double pulse sequence may display the short T2 components that appeared as low signal with conventional clinical MR imaging, which made it pessible to quantify the tissues containing a majority of short T2 components.
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BACKGROUND:During the restoration of residual molar crown, a little part of tooth is still remained commonly. After the restoration, with various forces, stress distribution affects directly the results after restoration. Finite element method is gradually applied in stress analysis on artificial tooth.OBJECTIVE: To establish the three-dimensional (3-D) finite element model of post-inlay restoration of the first residual mandibular molar crown so as to provide experimental data for improving model establishment of complicated teeth and analysis on the property of stress distribution of restoring methods.DESIGN: Repeated observation and measurement were given.SETTING: Department of Stomatology and Department of Radiology of First Hospital affiliated to Sun Yat-sen University;Department of Solid Mechanics,College of Traffics and Communications, South China University of Technology; Department of Restoration of Guanghua College of Stomatology.MATERIALS: The experiment was performed in Department of Solid Mechanics, College of Traffics and Communications of South China University of Technology from November 2003 to December 2004. Six first mandibular molars on the right side with normal morphology in vitro were collected, and Toshiba Xpress/SX spiral CT machine, image photo synthesis software and finite element analysis software ANSYS were applied in the experiment.METHODS: 1 of the 6 first mandibular molars on the right side with normal morphology in vitro was selected for pulpectomy, which was the best in density and near to clinical requirement in morphology. With pulpectomy, the prosthesis of braking-lock post-inlay restoration was prepared. Spiral CT-cross scanning was performed in premolar crown before the restoration, the residual crown with post-inlay in main root canal after restoration and the residual crown with braking-lock second post-inlay restoration. With image photosynthesis software, 3-D digital model of residual tooth and metal part was established and the entire tooth model was prepared after adhesion of two parts. In order to provide better boundary conditions of simulated natural tooth in practice, alveolar bone was considered. Under Mesh order in ANSYS software, automatic mesh generation was performed in the model directly.MAIN OUTCOME MEASURES: Establishment of 3-D finite element models of residual tooth before restoration, post inlay, and alveolar bone and tooth after restoration and the results of mesh generation.RESULTS: By establishing 3-D finite element models of residual tooth before restoration, post inlay, alveolar bone and tooth after restoration and automatic mesh generation, there were altogether 117720 units and 20988nodes. Good geometric similarity presents between the construction model of 3-D finite element model and solid tissue.CONCLUSION: Combination of 3-D finite-element model with spiral Ctcross technology establishes complex dental models, simulates practical conditions authentically and is good in operation.
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Objective To analyze the X -ray, CT, and MR imaging findings in osteoid osteoma. Methods Forty-eight cases of osteoid osteoma proved by surgical pathology were collected, including 33 males and 15 females. Among the 48 cases, all patients had plane films, 32 were imaged with CT scanning, 10 with MR imaging, and 8 with all three techniques. The imaging findings of osteoid osteoma and the ability of X-ray, CT, and MRI in demonstrating the nidus and the surrounding reaction were analyzed. Results The imaging manifestations of osteoid osteoma revealed a circular or oval nidus with different bone sclerosis around the nidus. The diameters ranged from 0.4 cm to 1.7 cm, with the average of 9.7 cm. There were also soft tissue and bone morrow edema around the nidus or distinct effusion of joint on MR imaging in all 10 cases. Among 48 cases, only 37 cases showed nidus on plane film. All 32 cases with CT scanning showed nidus. The display ratios of nidus were 77% for X-ray and 100% for CT, respectively. 10 cases with MR imaging could be diagnosed correctly. But the nidus could be affirmed in only 8 cases, and the nidus was affirmed by comparing with plane film or CT in the other 2 cases. Conclusion Nidus is the key in diagnosing the osteoid osteoma correctly. Plane film is still an important checking method for osteoid osteoma. CT scan is the best method to demonstrate the nidus. MRI can demonstrate the soft tissue and bone morrow edema around the nidus sensitively, but probably lead to an incorrect diagnosis. Combining with X-ray or CT, MRI can make an accurate diagnosis.
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Objective To analyze the MRI characters of Charcot joint, and to evaluate the diagnostic value of X-ray, CT, and MRI on Charcot joint. Methods Eight patients with 8 Charcot joints underwent X-ray, CT, and MR examinations. 6 of them had syringomyelia, 1 patient had injury of the spinal cord, and 1 case had diabetes. All 8 patients had sensory reduction or deficit in the sick extremities. Results There were two types of Charcot joint, hypertrophic and atrophic. Radiographic and CT features of hypertrophic joint (n=3) showed hyperostotic osteosclerosis and mammoth osteophytes in the sick bones, periarticular ossification,and articular disorganization. Radiographic and CT features of atrophic joint (n=5) showed extensive bone resorption (destruction), periarticular debris, and articular disorganization. Main MRI features of Charcot joint included hydrarthrosis within joint capsule, thickened, loose, and elongated joint capsule with para-joint, peri-diaphysis, and inter-muscular extension in a pseudopodia pattern. The irregular joint capsule wall was presented as mild hypointensity on T 1WI, slight hyper-intensity on T 2WI, and was markedly enhanced after Gd-DTPA was administrated, which was considered as a characteristic manifestation of the lesion. Soft tissue mass containing hypo-intense stripes on both T 1WI and T 2WI was commonly noted adjacent to the involved joint. Conclusion X-rays plain film is the first choice for the diagnosis of Charcot joint, and MRI is pretty useful in the diagnosis of Charcot joint.
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Objective To evaluate the value of MRI categorization of cholesteatoma of the skull base (CSB) and its MRI diagnostic characteristic Methods The CT, MRI and pathological data of 15 patients with CSB were reviewed The CSBs were categorized into type I and type II based on the difference of signal intensity on T 1 weighted image, and the differences between the two types of CSB were compared in the aspects of CT and MRI findings and osseous encroachment of the skull base Results Extremely high signal intensity on T 2 weighted image being similar to that of cerebrospinal fluid, and unenhanced tumor parenchyma on enhanced T 1 weighted image were noted in the 15 cases of CSB Of the 15 CSBs, 6 were categorized as type I and the other 9 as type II on the basis of the difference of the signal intensity on T 1 weighted image The 6 CSBs of type I, located in the prepontine and cerebellopontine angle cisterns, appeared as homogeneous hypoattenuating on CT scan and homogeneously decreased signal intensity on T 1 weighted image coupled with unenhanced tumoral capsule and relatively normal skull base The tumor parenchyma of this type was consisted of homogeneous cholesterol crystal The 9 CSBs of type II, located in unilateral floor of middle or posterior cranial fossa, were demonstrated as mixed density on CT scan and mixed signal intensity on T 1 weighted image, of which 4 presented as decreased signal intensity scattered with increased signal intensity, 5 largely as increased signal intensity The 9 cases were noted with enhanced tumoral capsule and marked osseous encroachment of the skull base, and the parenchyma of which was mainly comprised of keratinized epithelia and proteins Conclusion The categorization of CSB into type I and type II is sensible, which reflects the distinction in both histopathology and biological behaviour between the two types of CSB and plays an important role in guiding MRI diagnosis of CSB The MRI diagnostic characteristic of CSB includes the versatile signal intensity on T 1 weighted image, marked increased signal intensity on T 2 weighted image, unenhanced tumor parenchyma and type related osseous encroachment of the skull base
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Objective To determine the optimal sequences and scan parameters of Brachial Plexus MRI.Methods Eighteen volunteers were underwent conventional MRI and echo planar imaging scanning. The images acquired were compared with the standard anatomical pictures. Results Ventral rami, ganglion, trunks, cords and some peripheral nerves of brachial plexus were demonstrated very well by echo planar imaging with the post-processing techniques such as MIP, thin slice MIP and MPR.In 18/18 cases the postganglions on both sides and 17/18 cases the preganglions of brachial plexus on both sides could be visualized in EPI pre-processed and post-processed images.Conclusion Echo planar imaging is an effective technique of accurately displaying brachial plexus and adjacent structures. It has potential value in the diagnosis and treatment of brachial plexus diseases. It is also a potential technique to demonstrate other peripheral nerves accurately.
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Objective To probe the imaging diagnostic characteristics of skull base-type pituitary adenoma (SBPA). Methods CT, conventional MRI, dynamic MRI, and pathological data of 16 patients with SBPA were analyzed. The manifestations of both CT and conventional MRI, the dynamic time-signal curve, time of peak enhancement, and average enhancement rate were compared between SBPA in the 16 patients and chordoma of the skull base (CSB) in another 9 patients. Results The CT appearances of both tumors were quite similar, offering no differential value. Both tumors were slightly hypointense on T 1 weighted images, but SBPA was mildly hyperintense and CSB was markedly hyperintense on T 2 weighted images. The T 2 weighted signal intensity between both tumors differed significantly (P5 min, (40?5) /min for CSB, respectively (P