No abstract available.
Diagnosis*

PURPOSE: To obtain magnetization transfer ratio(MTR) of the annulus fibrosus and nucleus pulposus and to assess the feasibility of utilizing the changes of these MTRs as an early indicator of disk degeneration. MATERIALS AND METHODS: MR images of lumbar spine with magnetization transfer(MT) technique in 42 patients were obtained. spin echo techniques (600/14) with same TR/TE with 1KHz off-resonance saturation were employed in 1.0T MR system. MTRs were calculated in two regions, anterior annulus fibrosus and nucleus pulposus, and the results were compared between the normal and degenerative disks, from grade I to IV, on T2-weighted images. RESULTS: MTRs of the nucleus pulposus were 17.6% in the normal disks, and 26.7%, 28.4%, 29.1%, 29.7% in degenerative disks, from grade I to IV, respectively, with a significant difference(P<0.05). On the other hand, MTRs in the annulus fibrosus were 30.2% in the normal disks and 31.5%, 33.2%, 32.1% and 35.6% in degenerative disks, from grade I to IV, respectively, without significant difference. CONCLUSION: Since MTRs are significantly higher in degenerative nucleus pulposus than those of the normal disks, increased MTRs in the nucleus pulposus can be used as an early sign of the degeneration of the nucleus pulposus.
Hand ; Humans ; Intervertebral Disc Degeneration* ; Magnetic Resonance Imaging* ; Spine

PURPOSE: Magnetization transfer imaging(MTI) is a new imaging contrast technique. Our MT pulse sequence is designed as fixed time interval between echo and MT pulse. This study was peformed to evaluate the influence of variations in TR/TE on MTR in T1 weighted image of normal brain tissue on this kind of MT pulse sequence. MATERIALS AND METHODS: Seven healthy volunteers in twenties of age as the objectives, MRI was taken under various TR/TE(TR/TE ;700/14, 650/14, 750/14, 700/20 and 1500/20 msec). MTR was calculated from signal intensities measured at the same point in both pre and post MT images and statisticslly analyzed. The MR imager used in this study was 1.0T Magnetom 42SP(Siemens, Erlangen, Germany) and the parameters of additional MT pulse sequence were offset 1000Hz and bandwidth 250Hz, and posteriorly located to echo with 7.7 msec fixed interval. Offset of this MT pulse was variable. RESULT: In white matter of brain tissue from a normal person, MTR was 34-39%(average 37%) for TR and TE of 700/14 in T1WI and 33-36%(average 35%) for TR/TE of 650/14, and 34-38%(average 35%) for TR/TE of 750/14 which showed no statistical difference. However, in case of 1500/20 of TR/TE, MTR was 26-28%(average 26%) which is statistically significant. With TR/TE of 700/14 as the standrd value, the MTR of gray and white matter were 37% and 29% respectively, showing a definite difference of statistical means. Signal from CSF in ventricles is rarely influenced by MT pulse. CONCLUSION: Conclusively, a subtle variation in TR/TE in T1WI has little influence on MTR but wide range of variation in TR/TE as in proton density image induces significant difference in MTR on this kind of MT pulse sequence. Therefore, the exchangeable usage of MTR data would be possible in narrow range of TR/TE change but difficult in wide range of variation.
Brain* ; Healthy Volunteers ; Humans ; Magnetic Resonance Imaging ; Protons ; Reference Values*

PURPOSE: The purposes of this study were to analyze the MR findings of medulloblastoma, and to evaluate the subarachnoid dissemination and the significance of contrast enhanced MR of brain and spine for tumor.. MATERIALS AND METHODS: The preoperative brain MR studies of 18 patients (9 males, 9 females;mean age, 9.4 years) with surgically proved medulloblastomas were retrospectively reviewed to characterize these neoplasms with regard to their location, size, MR signal intensity, appearance after contrast enhancement, presence of cyst and necrosis, subarachnoid dissemination, and other associated findings. In 14 patients postoperative spine MR studies were evaluated for staging and therapeutic planning. RESULTS: The most frequent location of medulloblastoma was the inferior vermis and the mean tumor size was 4.1 x 3.6 x 3.9 cm. On Tl-weighted image, medulloblastomas generally had low to intermediate signal, predominantly hypointense relative to white matter. On T2-weighted image, medulloblastomas showed modetately high signal, hyperintense relative to white matter. Inhomogeneous contrast enhancement was demonstrated in 13 patients(72.2%) after injection of gadopentetate dimeglumine(Gadolinium). Cyst and necrosis within the tumor were visualized in 15 patients(83.3%). Subarachnoid disseminations of medulloblastomas were noted in 11 patients(61.1%), of which 6 demonstrated intracranial and 2 intraspinal dissemination. Three had both intracranial and intraspinal dissemination. In nine cases with intracranial lesions, there were intraparenchymal mass formation(7), subarachnoid nodules(5), infundibular lesions(2) and diffuse gyral enhancement(I). In five cases with intraspinal lesions, there were extramedullary intradural small nodules(3), central canal nodules(2), intradural masses(I)and fine nodular and sheet-like leptomeningeal enhancement(1). Other associated findings included intratumoral hemorrhage(11.1%), per/tumoral edema(44.4%), tonsillar herniation(44.4%), hydrocephalus(88.9%) and calcification(44.4%). CONCLUSION: Medulloblastomas revealed low to intermediate signal intensity on Tl-weighted image and intermediate to moderately high signal intensity on T2-weighted image, relative to cerebellar white matter. Medulloblastomas were solid tumors with cystic necrosis, which showed inhomogeneous enhancement and subarachnoid disseminations to the intracranial and intraspinal spaces after Gd-DTPA enhancement. Gd-enhanced MR of brain and spine was an useful diagnostic modality in preoperative diagnosis and in staging of postoperative cases of medulloblastomas, which was superior to postcontrast CT or precontrast MR.
Brain* ; Diagnosis ; Gadolinium DTPA ; Humans ; Male ; Medulloblastoma ; Necrosis ; Retrospective Studies ; Spine*

The globus symptom is a condition in which a patient, often middle aged women, complains of a lump andchocking sensation in the throat, Functional disturbance of the cricopharyngeal muscle, rendering it incapable ofrelaxing during swallowing, has long been recognized as a cause of globus symptom and dysphagia. We wanted to findout how often and to what extent distrubed relaxation of the cricopharyngeal muscle can be seen in patients withglobus symptom with routine examination and video esophagogram. The results were as follows: 1. Male : femaleratio was 1:2.4. 2. Globus symptom was most frequent in the age group between 30-39 of female. 3. Organic lesionswere seen in 43.6%(24 Pts) of globus patients. 4. Cricopharyngeal muscle was visualized in 29.1%(16Pts), esophageal diverticulum in 3.6%(2 Pts) and degenerative spondylosis in 3.6%(2 Pts). 5. Incidence of visualizationof cricopharyngeal muscle were higher in male group (50%) than female one (20.5%). 6. Cricopharyngeal muscle wasmost frequently visualized on early swallowing phase(12/16 Pts).
Deglutition ; Deglutition Disorders ; Diverticulum, Esophageal ; Female ; Humans ; Incidence ; Male ; Middle Aged ; Pharynx ; Relaxation ; Sensation ; Spondylosis

No abstract available.
Thanatophoric Dysplasia*

PURPOSE: A common finding of carotid artery on magnetic resonance angiograms(MRAs) is a signal dropout along the posterior wall of carotid bulb due to reverse flow. The purpose of this study is to evaluate variable flow patterns on bifurcated carotid arterial phantoms using steady-state flow. MATERIALS AND METHODS: We designed phantoms of a bifurcated carotid artery with acrylic materials. Flow patterns were evaluated with axial and coronal imaging of MRA(2D-TOF, 3D-TOF), color Doppler imaging, and computational fluid dynamics (CFD) within the phantoms constructed of an automated closed-type circulatory system filled with 4% sugar solution. These findings were compared with findings obtained from normal volunteers. RESULTS: Axial 3D-TOF MRA images exhibited closer resemblance to the contour of the inner wall of phantoms when compared to coronal 2D-TOF MRA imaging. However, 2D-TOF MRA showed good contrast difference of signal intensities between forward flow area and reverse flow area. Dark zones with reduced signal intensities due to reversed flow were separated from the outer wall of the internal and external carotid arteries by a thin layer of forward flow along the wall on the source slice image of MRA. The general hemodynamics of the phantoms on MRA were identical to hemodynamics on color Doppler imaging and CFD. The results obtained with the phantoms matched the findings on normal volunteers. CONCLUSION: Although representations of bifurcated carotid arterial phantoms on axial 3D-TOF MRA were excellent if ideally desinged, the zone of reversed flow could be a significant factor in creating distorted image when the zone of reversed flow contacted directly with curved or deformed arterial wall.
Carotid Arteries ; Carotid Artery, External ; Healthy Volunteers ; Hemodynamics ; Humans ; Hydrodynamics ; Magnetic Resonance Angiography* ; Patient Dropouts

PURPOSE: Pilocytic astrocytoma is a benign tumor predominantly arising from cerebellum in pediatric age. But it occasionally arises in supratentorium. We describe radiologic findings of supratentorial pilocytic astrocytoma. MATERIALS AND METHODS: Eleven CT and 7 MR examinations in 11 patients were retrospectively reviewed with attention to location, CT density, MR signal intensity, and degree and pattern of contrast enhancement on CT and MR. RESULTS: The tumors were located around the third ventricle (hypothalamus in three cases, optic chiasm in three cases) and in cerebral hemisphere (temporal lobe in three cases, frontal lobe in one case, thalamus in one case). On CT, the tumors were all sharply demarcated and rarely associated with edema. The tumors showed moderate to strong contrast enhancement. Necrosis appeared frequently in tumors around the third ventricle in contrast to frequent cyst formation in hemispheric masses. On MR, the tumors appeared hypo- or isointense on T1- weighted images and hyperintense on T2- weighted images. After administration of contrast agent, the tumors showed intense enhancement more than that of CT. CONCLUSION: The typical location and radiologic findings described above are helpful in the diagnosis of the supratentorial pilocytic astrocytoma.
Astrocytoma* ; Cerebellum ; Cerebrum ; Diagnosis ; Edema ; Frontal Lobe ; Humans ; Necrosis ; Optic Chiasm ; Retrospective Studies ; Thalamus ; Third Ventricle

PURPOSE: To evaluate the characteristic color Doppler imaging of vertebral artery flow in the subclavian steal phenomenon. MATERIALS AND METHODS: The study group consisted of eight patients with reversed vertebral artery flow proved by color Doppler imaging. We classified this flow into two groups : (1) complete reversal ; (2)partial reversal, as shown by Doppler velocity waveform. Vertebral angiography was performed in six of eight patients ; color Doppler imaging and angiographic findings were compared. RESULTS: On color Doppler imaging, all eight cases with reversed vertebral artery flow showed no signal at the proximal subclavian or brachiocephalic artery. We confirmed shunting of six cases by performing angiography from the contralateral verterbral and basilar artery to the ipsilateral vertebral artery. On the Doppler spectrum, six cases showed complete reversal and two partial reversal. On angiography, one partial reversal case showed complete occlusion of the subclavian artery with abundant collateral circulation of muscular branches of the vertebral artery. CONCLUSION: On color Doppler imaging, a reversed vertebral artery suggests the subclavian steal phenomenon. In particular, partial reversal waveform may reflect collateral circulation.
Angiography ; Arteries ; Basilar Artery ; Collateral Circulation ; Humans ; Subclavian Artery ; Subclavian Steal Syndrome* ; Vertebral Artery

PURPOSE: To evaluate the relationship between spinal instability and ossification of the posteriorlongitudinal ligament(OPLL). MATERIALS AND METHODS: In 70 patients(M:F=45:25, mean age=53years) diagnosed as OPLLon the bosis of with surgical operation field findings and radiological evaluation[ plain film(n=70), CT(n=64),MRI(n=55) ], involved levels were the cervical spine(n=32), lumbar spine(n=23), and both the cervical and lumbarspine(n=15). Spinal instability was radiologically diagnosed as horizontal displacement of one vertebra by anotherof more than 3.5mm, or a difference in rotation from either adjacent vertebra by more than 11degree in lateralcervical spine and a difference of more than 1.5mm from the posterior body margins to the point of intersection oftwo lines drawn parallel to the opposing segmental endplate in extension lateral lumbar spine. We divided OPLLinto group I(continuous, segmental, mixed) and group II(retrodiscal), and compared spinal instability in these twogroups. RESULTS: In cervical OPLL, group I comprised 33 cases and group II 14. In group I, spinal instability wasnoted in 8/33 cases(24%)) or 10/123 segments(8.1%). Spinal instability in group II, on the other hand, was foundin 13/14 cases(93%) or 17/26 segments(65%). Ossification occurred at the retrodiscal level in 37 cases, byt incase was continuous. In group II, spinal instability was found in 25 of 37 cases(69%), oe in 29 of 55segments(53%). CONCLUSION: Compared to other types of OPLL, the frequency of retrodiscal OPLL in association withspinal instability was high. Spinal instability may thus be the most important cause of retrodiscal OPLL.
Hand ; Spine