MR imaging findings of paravertebral gossypiboma.

BACKGROUND AND PURPOSE: "Gossypiboma" is a term used to describe a mass within the body that comprises a cotton matrix surrounded by a foreign-body reaction, which is extremely rare after spinal surgery. The purpose of this study was to describe the clinical and MR imaging features of gossypibomas in the paravertebral area of 7 patients. MATERIALS AND METHODS: Between October 1999 and December 2005, 7 cases of paravertebral gossypibomas were confirmed pathologically at 2 institutions. The clinical features were reviewed retrospectively. We recorded MR imaging features and differential MR imaging-based diagnoses. RESULTS: All patients were symptomatic; the most frequent symptom was nonspecific back or neck pain. None of the patients presented with signs of infection or required surgery urgently. In 3 of the 7 patients, gossypiboma was included in the preoperative differential imaging diagnosis. In all patients, the gossypiboma was located in the vicinity of the initial site of surgery. Typically, gossypibomas were visible in T2-weighted images as a mass with a hyperintense center and hypointense rim and exhibited strong peripheral enhancement in contrast-enhanced images. Retained surgical gauze was removed surgically from 4 patients; in the remaining patients, the surgical specimens contained suture threads. CONCLUSION: Gossypiboma should be included in the differential diagnosis of the paravertebral mass when a mass with a hyperintense center and peripheral hypointense rim on T2-weighted images and strong peripheral rim enhancement on contrast-enhanced T1-weighted MR images is seen in postoperative patients.

Protective effect of agmatine on a reperfusion model after transient cerebral ischemia: Temporal evolution on perfusion MR imaging and histopathologic findings.

BACKGROUND AND PURPOSE: The goal of thrombolytic therapy in patients with acute ischemic stroke is early recanalization, but this may result in delayed reperfusion injury. The purpose of this study was to evaluate the neuroprotective effect of agmatine in a transient ischemic cat model by using MR perfusion imaging and histopathologic analyses. METHOD: One-hour temporary occlusion of the left middle cerebral artery of cats was performed in the control ischemia group (n = 10), and 100 mg/kg of agmatine was intravenously injected immediately after recanalization in the agmatine-treated group (n = 15). MR imaging was performed at 1, 24, and 48 hours after recanalization, and the perfusion patterns were investigated. Terminal-deoxynucleotidyl transferase mediated nick and end-labeling (TUNEL) and hematoxylin-eosin (H&E) stainings were performed at the corresponding sections. RESULTS: In the control ischemia group, the number of TUNEL-positive cells was significantly increased in the areas with reperfusion hyperemia (P < .05). In the agmatine-treated group, no significant increase in the number of TUNEL-positive cells was noted in the areas of reperfusion hyperemia. The difference in the number of TUNEL-positive cells between the control ischemia and agmatine-treated group in the areas of reperfusion hyperemia was significant (P < .05). The total number of TUNEL-positive cells and the area of severe ischemic neuronal damage on H&E stain were also significantly attenuated in the agmatine-treated cats compared with the control ischemia cats (P < .05). CONCLUSION: Our results suggest that agmatine has neuroprotective effects against reperfusion injury and ischemia.

Results of transvenous embolization of cavernous dural arteriovenous fistula: a single-center experience with emphasis on complications and management.

BACKGROUND AND PURPOSE: To describe the results of transvenous embolizations of cavernous dural arteriovenous fistua (cDAVF) with an emphasis on identifying the incidence, characteristics, and management strategies associated with the complications of transvenous embolization of cDAVFs. METHODS: Fifty-six consecutive patients who were treated by transvenous embolization for cDAVFs were reviewed. The approach routes, angiographic results, complications, and clinical outcome were assessed. RESULTS: Retrograde inferior petrosal sinus (n = 36), transfacial vein (n = 7), transcontralateral intercavernous sinus (n = 4), and direct superior ophthalmic vein (n = 3) approaches were used. Angiographic results showed complete occlusion (n = 29), nearly complete occlusion (n = 13), and incomplete occlusion (n = 14). Complications associated with the procedures were cranial nerve palsy (n = 6), venous perforation (n = 3), and brain stem congestion (n = 2). The cranial nerve signs resolved with conservative treatment. Venous perforations were managed by coil embolizations at the site of the tear with no significant neurologic sequelae. One case of brain stem congestion resulted in hemiplegia after conservative treatment. The other case showed venous congestion as a result of rerouting of the shunted flow after venous embolization that was successfully managed by covered stent deployment for occlusion of the residual feeders. Clinical follow-up data were available in 46 patients. Complete resolution or improvement of symptoms was seen in 42 patients (91%). CONCLUSIONS: Cavernous DAVFs may be effectively treated by transvenous embolization. However, the procedure can be associated with various complications, some of which can potentially result in significant morbidity. Prompt diagnosis of the complications with appropriate management strategies is mandatory for a safe procedure.

Management of hypertension by private doctors in Hong Kong.

OBJECTIVE: To investigate the management of hypertension by private doctors in Hong Kong. DESIGN: Self-administered questionnaire survey. SETTING: Hong Kong. PARTICIPANTS: Private doctors from all districts in Hong Kong selected by simple random sampling from the website of "The Hong Kong Doctors Homepage" from March to June 2005. MAIN OUTCOME MEASURES: Practice of blood pressure measurement and the treatment prescribed to hypertensive patients. RESULTS: A total of 225 (46%) completed questionnaires were analysed. Only 24.4% of the respondents measured blood pressure in all new patients aged above 18 years. A total of 28.0% of doctors reported that hypertensive status was unknown in over 30% of their patients prior to their first clinic visit when it was consequently diagnosed. Calcium channel blockers (31%), angiotensin-converting enzyme inhibitors (28.5%), diuretics (27.5%), and beta-blockers (21.2%) were the most commonly prescribed antihypertensive medication. Drug efficacy was the reason cited by more than half (56.9%) of doctors for selecting a given drug. Public education about hypertension was considered insufficient by 66.2% of doctors and 32% believed that self-medication would have a very significant effect on drug compliance. CONCLUSIONS: In private clinics, blood pressure measurement should become a routine procedure. There is a need to raise public awareness of hypertension.

Hemidystonia and hemichoreoathetosis as an initial manifestation of moyamoya disease.

OBJECTIVE: To describe hemidystonia and hemichoreoathetosis in an adult patient with moyamoya disease without a previous history of cerebrovascular accident. DESIGN: Case report. SETTING: Tertiary care center. PATIENT: A 22-year-old woman suddenly developed dystonic spasms in her left hand and left foot after a severe emotional stress. The dyskinesia gradually subsided over the next 4 months. Five months after the onset, she suddenly developed choreoathetoid movement in her right hand and right foot. MAIN OUTCOME AND RESULTS: The patient had both somatic and cortical sensory deficits in the right hand and right foot. Magnetic resonance imaging of the brain showed an infarction at the right putamen and lesions involving the right frontal lobe and the left frontotemporoparietal lobe. Magnetic resonance cerebral angiography showed severe stenoses of both internal carotid arteries at the supraclinoid portion and numerous collateral vessels, compatible with moyamoya disease. Single photon emission tomography of the brain showed hypoperfused areas at the right frontal and left frontotemporoparietal lobes. The choreoathetosis of the right limbs improved markedly, along with improvement of sensory deficits. CONCLUSIONS: To our knowledge, this is the first report of an adult patient presenting with hemidystonia and hemichoreoathetosis as the initial manifestations of moyamoya disease. Arch Neurol. 2000;57:1510-1512

Increased cerebral perfusion after detachable balloon embolization of carotid cavernous fistula on technetium-99m-HMPAO brain SPECT.

Most symptoms and signs associated with a carotid cavernous fistula (CCF) are thought to be related to regurgitation of flow into cortical veins and to venous congestion. Arteriovenous shunting and secondary perfusion insufficiency is regarded as less important in causing symptoms. We describe a 27-yr-old male patient who had improvement of neurologic symptoms and signs after detachable balloon embolization of traumatic CCF. The pre- and postocclusion 99mTc-HMPAO brain SPECT scan showed improved cerebral blood flow after occlusion. The CCF had shown marked arteriovenous shunting without significant venous congestion on pre-occlusion cerebral angiogram. The postocclusion cerebral angiogram revealed complete occlusion of the CCF with increased blood flow in the ipsilateral middle cerebral artery distribution. These findings suggest that cerebral dysfunction may be related to perfusion insufficiency from the CCF. Brain SPECT scanning can assess the functional status of cerebral perfusion and may be a useful, noninvasive adjunct to angiography.

Increased contralateral cerebellar uptake of technetium-99m-HMPAO on ictal brain SPECT.

UNLABELLED: Crossed cerebellar diaschisis (CCD) is a well-known brain SPECT finding in stroke patients. Two reports, however, have described supratentorial and contralateral cerebellar hyperperfusion (crossed cerebellar hyperperfusion) on ictal brain SPECT in epileptic patients. The purpose of this study was to assess the usefulness of crossed cerebellar hyperperfusion (CCH) for the detection of epileptic foci on ictal scan. METHODS: Twelve patients with complex partial seizures having characteristic clinical, electroencephalographic (EEG) and brain SPECT findings were included. Fifteen to 20 mCi 99mTc-HMPAO were injected intravenously during the seizure period or the aura for the ictal SPECT study. The SPECT findings were visually assessed to determine whether the finding of CCH was valuable in the localization of ictal foci. RESULTS: Epileptic foci were found in the right temporal (n = 6), left temporal (n = 4), right occipital (n = 1) and left frontal (n = 1) areas. CCH was observed in 8 (75%) of the 12 patients. In two patients, contralateral cerebellar uptake was more obvious than that in the epileptic foci. In the interictal scans, cerebellar activity, which was increased in ictal period, was equalized in seven of eight patients, while perfusion was diminished in the remaining patient. CONCLUSION: CCH is a frequent finding of ictal brain SPECT and may aid in the lateralization of epileptic foci.

HMPAO SPECT to assess neurologic deficits during balloon test occlusion.

UNLABELLED: The purpose of this study was to determine if one could objectively and preoperatively predict the safety of permanent occlusion of an internal carotid artery with 99mTc-HMPAO brain SPECT. METHODS: Twenty-four patients underwent balloon test occlusion of the internal carotid arteries because of neck and skull base tumors. We assessed the uptake of both middle cerebral artery territories before and during balloon test occlusion with 99mTc-HMPAO brain SPECT using the semiquantitative analysis. The results were compared with other factors, including neurologic examination, arterial stump pressure and electroencephalogram. RESULTS: Nineteen patients experienced no neurological deterioration or any problem during balloon test occlusion. The comparative uptake of their middle cerebral artery territories was 95%-101% of the pre-balloon test occlusion state. The remaining five patients showed severe neurologic symptoms, such as transient hemiplegia and unconsciousness. The comparative uptake of their middle cerebral artery territories was 77%-85% of the pre-balloon test occlusion state and was well matched with other factors. CONCLUSION: Technetium-99m-HMPAO brain SPECT before and during balloon test occlusion seems to be a simple and objective method for predicting permanent neurologic deficits when the comparative uptake of middle cerebral artery territories during balloon test occlusion is less than 85% of that before balloon test occlusion.

Morphology, drug distribution, and in vitro release profiles of biodegradable polymeric microspheres containing protein fabricated by double-emulsion solvent extraction/evaporation method.

The surface and internal morphology, drug distribution and release kinetics at 22 degrees C of polyesters such as PCL (polycaprolactone) and PLGA (poly(DL-lactic-co-glycolic acid)) 65:35 microspheres containing BSA (bovine serum albumin) have been investigated in order to understand the relationship amongst morphology, drug distribution and in vitro release profiles and to develop controlled release devices for marine fishes in tropical area. CLSM (confocal laser scanning microscope) micrographs reveal that the polyvinylalcohol (PVA as an emulsifier) concentration in the external water phase strongly influences drug distribution within microspheres and release profiles. The presence of PVA in the internal water phase enhances the stabilization of inner water droplets against coalescence. This results in a more uniform drug distribution and a slower BSA release. Different oil-phase volumes and polymer concentrations yield different solvent exchange and precipitation mechanisms, which lead to different morphologies. A low oil-phase volume yields microspheres with a porous matrix and defective skin surface, which gives a high initial BSA burst as well as a fast release profile. Microspheres fabricated from a low polymer concentration have less defective skin surface, but with a less tortuous inner matrix which results in a more rapid BSA release. A higher BSA loading yields a larger concentration gradient between the emulsion droplet and the continuous water phase as well as between the microspheres and the in vitro medium. The former results in a lower encapsulation efficiency, whereas the latter yields a faster initial burst and a more rapid release profile. High stirring speed can reduce microsphere size, but decreases the yield of microspheres.

Wilms tumor in adults.

Wilms tumor rarely occurs during adult life. We have found 197 such cases reported in the world literature. However, there are some controversies whether all of these are true Wilms tumors or rather a variety of adenocarcinomas or sarcomatoid renal cell carcinoma. We report here 2 additional cases of well-documented Wilms tumors in adults.

Effect of preparation temperature on the characteristics and release profiles of PLGA microspheres containing protein fabricated by double-emulsion solvent extraction/evaporation method.

This study describes the influence of preparation temperature on the various characteristics and release profiles of poly(DL-lactide-co-glycolide) (PLGA) microspheres. The bovine serum albumin (BSA)-loaded microspheres were prepared using the water-in-oil-in-water (w/o/w) technique with poly(vinyl alcohol) as surfactant in the external aqueous phase. We have varied the preparation temperature to observe its effect on microsphere characteristics such as the microsphere shrinking rate during formation, particle size, density, surface and internal morphology, BSA encapsulation efficiency, BSA initial release, microsphere degradation and BSA in vitro release behaviour. During fabrication, a low preparation temperature of 5 degrees C gives the fastest initial but the slowest overall shrinking rate. Microspheres formed at high temperatures of 38 degrees C and 42 degrees C on the other hand have the lowest initial yet the highest overall shrinking rate. Subsequently, microsphere mean size increases and the particle size distribution widens with increase in the preparation temperature. Although all the microspheres have a porous surface as well as internal structure, microspheres fabricated at high temperatures have a uniform internal pore distribution and a very thin dense skin layer, while microspheres fabricated at lower temperatures have a thicker but porous skin layer and bigger pores in the middle of the sphere. Microspheres formed at 33 degrees C are found to give the highest initial burst release. In terms of in vitro release, microspheres fabricated at low temperatures (5 degrees C, 15 degrees C and 22 degrees C) exhibit similar, steady rates. Microspheres formed at higher temperatures however give very low release rates after their initial release. The results obtained suggest that preparation temperature significantly affects microsphere formation, resulting in their structural and protein release profile differences. These differences ultimately work together to affect the initial release and overall release patterns of the microspheres.

Auto-catalyzed poly(ortho ester) microspheres: a study of their erosion and drug release mechanism.

A study has been carried out to investigate the degradation and protein release mechanisms of BSA-loaded microspheres made with auto-catalyzed poly(ortho esters) (POEs) of varying diol composition and molecular weights. Due to the instability of the POE/dichloromethane primary emulsion, microspheres made using the W/O/W double emulsion solvent extraction/evaporation method showed a multivesicular internal structure. An O/W single emulsion process yielded dense POE microspheres. Using electron scanning microscopy, the microspheres were observed to erode throughout their matrices with increasing internal pore sizes and a steady loss of mass. However, despite a substantial weight loss of almost 80% after an in vitro period of 129 days, the molecular weight of the polymer remained relatively unchanged with loss averaging about 18 and 32% for low- and high-molecular-weight POEs, respectively. Such constancy in molecular weight was similarly reflected in the glass transition temperature of the degrading microspheres. The differences in both the molecular weight loss and polydispersity index changes depended largely on the molecular weight of the polymer. For protein release of POE microspheres, an induction period followed by BSA release for a period of 3 to 10 days was observed. The lag time depended on the hydrophilicity and the molecular weight of the polymer as well as the morphology of the microspheres. Protein release was incomplete, possibly due to the slow degradation of the POE polymers, protein aggregation and protein degradation.

POE-PEG-POE triblock copolymeric microspheres containing protein. I. Preparation and characterization.

Poly(ortho ester) (POE)-poly (ethylene glycol) (PEG) triblock copolymers (POE-PEG-POE) with different PEG contents were synthesised as carriers for controlled protein delivery. POE-PEG-POE microspheres containing bovine serum albumin (BSA) were prepared using a double-emulsion (water-in-oil-in-water) process. In this first paper of a two-part series, we report the fundamentals of the fabrication and characterization of POE-PEG-POE microspheres. Because the triblock copolymer is more hydrophilic than neat poly(ortho ester), the triblock copolymer yields a more stable first emulsion (water-in-oil) and a greater BSA encapsulation efficiency (90% vs. 30%). No BSA is found on POE-PEG-POE microsphere surfaces measured by X-ray photoelectron spectroscopy, while uniform BSA distributions are observed within the microspheres by confocal microscopy. SEM pictures show that an increase in PEG content results in microspheres with a denser cross-section because of a more stable first emulsion and better affinity between the copolymer and water. POE-PEG(20%)-POE suffers significant swelling during the fabrication process and yields the biggest microspheres. However, the POE-PEG(30%)-POE microspheres are much smaller since the dissolution loss of POE-PEG(30%)-POE in the external water phase may be much higher than that of POE-PEG(20%)-POE. The salt concentration in the external water phase significantly affects the morphology of the resultant microspheres. Microspheres with a dense wall are produced when using pure water as the external water phase. Polymer concentration has less impact on BSA encapsulation efficiency but has a considerable effect on microsphere size and morphology. Increasing the concentration of the polyvinyl alcohol emulsifier does not cause an obvious decrease in microsphere size. However, increased BSA loading results in bigger microspheres.

POE-PEG-POE triblock copolymeric microspheres containing protein. II. Polymer erosion and protein release mechanism.

The first paper of this series presented the fabrication and characterization of POE-PEG-POE triblock copolymeric microspheres containing protein. In this paper, we focus on the polymer erosion and the mechanism of protein release. Fourteen-week in vitro behaviors of POE-PEG-POE microspheres loaded with bovine serum albumin (BSA) have been monitored. SEM micrographs reveal that after 14-week incubation in PBS buffer, pH 7.4, 37 degrees C, the polymeric particles remain spherical despite mass loss of almost 90%. On the other hand, molecular weight undergoes a high initial loss of 38% and 44% during the first 2-week incubation for POE-PEG(5%)-POE and POE-PEG(10%)-POE, respectively. Then, it keeps relatively unchanged over 12 weeks. However, POE-PEG(20%)-POE copolymer provides a better compatibility between the POE and PEG blocks. Hydrolysis is homogeneous through the polymer backbone. Thus, its molecular weight remains relatively constant and mass loss shows quite sustained over the 14-week in vitro release. The similar phenomena are observed in the polydispersity index of the degrading copolymers. SDS-PAGE of the encapsulated BSA within the POE-PEG(5%)-POE microspheres displays that the structural integrity of BSA is intact for at least 8 weeks due to a mild environment provided by the copolymer. In addition, XPS and FTIR are utilized to investigate protein behaviors in the degrading microspheres. Protein release from the POE-PEG-POE microspheres shows a biphasic pattern, characterized by an initial stage followed by a non-detectable release. The non-release phase is dominated by either slow polymer degradation or dense microsphere matrix structures. The microsphere formulation is optimized and a sustained protein release over 2 weeks is achieved by using POE-PEG(20%)-POE at a high protein loading.

Evaluation of cerebral aneurysms with high-resolution MR angiography using a section-interpolation technique: correlation with digital subtraction angiography.

BACKGROUND AND PURPOSE: The objective was to evaluate the results of high-resolution, fast-speed, section-interpolation MR angiography and digital subtraction angiography (DSA), thereby examining the potential use of a primary noninvasive screening test for intracranial aneurysms. METHODS: The images were obtained in 39 cerebral aneurysmal lesions from 30 patients with a time-of-flight MR angiographic technique using a 1.5-T superconducting MR system. The total image volume was divided into four slabs, with 48 partitions each. To save time, only 24 phase-encoded steps were measured and interpolated to 48. The parameters used included 30/6.4 (TR/TE), a flip angle of 25 degrees , a 160x512 matrix, a field of view of 150x200, 7 minutes 42 seconds of scan time, an effective thickness of 0.7 mm, and an entire thickness of 102.2 mm. Maximum intensity projection was used for the image analysis, and a multiplanar reconstruction technique was used for patients with intracranial aneurysms. RESULTS: Among 39 intracranial aneurysmal lesions in 30 patients, 21 were ruptured and 18 were unruptured. Twelve lesions were less than 2 mm in size, 12 were 3 to 5 mm, 12 were 6 to 9 mm, and three were larger than 10 mm. At initial examinations, 38 of 39 aneurysmal lesions were detected by both MR angiography and DSA, with 97% sensitivity. In confirming aneurysms in neck and parent vessels, multiplanar reconstruction was successful in detecting all 39 aneurysms, whereas MR angiography was successful in detecting 27 (69%) and DSA was successful in detecting 32 (82%) of the lesions. CONCLUSION: High-resolution MR angiography with a section-interpolation technique showed equal results to those of DSA for the detection of intracranial aneurysms and may be used as a primary noninvasive screening test. In the evaluation of aneurysms in neck and parent vessels, the concurrent use of MR angiography and multiplanar reconstruction was far superior to the use of either MR angiography or DSA alone.

Kikuchi disease: CT and MR findings.

Two cases of Kikuchi disease showed variable nodal enhancing features, including homogeneous enhancement and focal or extensive nodal necrosis on contrast-enhanced CT scans. At MR imaging, the area of central necrosis was isointense or hypointense on T1-weighted images and had a lower signal than nonnecrotic areas on T2-weighted images. The CT appearance of Kikuchi disease can be variable and can mimic not only lymphoma but various nodal diseases with nodal necrosis, including metastasis and tuberculosis.

The role of functional MR imaging in patients with ischemia in the visual cortex.

BACKGROUND AND PURPOSE: Functional MR (fMR) imaging is based on changes in regional blood flow. The purpose of this study was to evaluate the role of fMR imaging for detection of a vascular compromised status in the occipital lobe in patients with ischemia in the visual cortex. METHODS: We performed fMR imaging in seven control subjects and seven patients with symptoms and signs of visual cortical transient ischemia and/or infarct. fMR imaging was performed using a gradient-echo sequence with the 2D fast low-angle shot technique. An axial slice including both visual cortices was selected, and stimulation of the visual cortex was performed using a red photostimulator. The number of activated pixels in each primary visual cortex area were counted and an asymmetry ratio [AR (%) = 100 x (R-L)/(R+L)/2] was calculated. Patients and control subjects underwent visual field examination, conventional MR imaging, and vascular imaging (MR angiography in all patients and control subjects, conventional catheter angiography in two patients). fMR imaging results were compared with the results of a visual field examination, conventional MR imaging, and vascular imaging. RESULTS: fMR imaging of the patients showed significant activation asymmetry (P <.05) compared with that of control subjects. Vascular abnormalities in the posterior circulation were found in all seven patients. By conventional MR imaging, five patients were found to have infarction in the occipital lobe and the remaining two patients showed no abnormality. In visual field examination, six of the seven patients showed homonymous hemi- or quadrantanopsia suggesting postchiasmic abnormalities, and the remaining patient had normal findings. fMR imaging showed decreased activity in the visual cortices corresponding to vascular abnormalities (seven of seven patients), permanent infarction (five of seven patients), or visual field defect (six of seven patients). Two patients with normal conventional MR imaging had vascular lesions in the posterior circulation, and fMR imaging showed decreased activity in the corresponding visual cortices. One patient with normal visual field examination had multifocal stenosis in the posterior cerebral artery without infarction, and fMR imaging showed decreased activity in the corresponding visual cortex. CONCLUSION: fMR imaging of the visual cortex may be a sensitive method for the detection of vascular-compromised status in the occipital lobe.

Transient MR signal changes in patients with generalized tonicoclonic seizure or status epilepticus: periictal diffusion-weighted imaging.

BACKGROUND AND PURPOSE: Our purpose was to investigate transient MR signal changes on periictal MR images of patients with generalized tonicoclonic seizure or status epilepticus and to evaluate the clinical significance of these findings for differential diagnosis and understanding of the pathophysiology of seizure-induced brain changes. METHODS: Eight patients with MR images that were obtained within 3 days after the onset of generalized tonicoclonic seizure or status epilepticus and that showed seizure-related MR signal changes had their records retrospectively reviewed. T1- and T2-weighted images were obtained of all eight patients. Additional diffusion-weighted images were obtained of five patients during initial examination. After adequate control of the seizure was achieved, follow-up MR imaging was performed. We evaluated the signal changes, location of the lesions, and degree of contrast enhancement on T1- and T2-weighted images and the signal change and apparent diffusion coefficient (ADC) on diffusion-weighted images. We also compared the signal changes of the initial MR images to those of the follow-up MR images. RESULTS: The initial MR images revealed focally increased T2 signal intensity, swelling, and increased volume of the involved cortical gyrus in all eight patients. The lesions were located in the cortical gray matter or subcortical white matter in seven patients and at the right hippocampus in one. T1-weighted images showed decreased signal intensity at exactly the same location (n = 6) and gyral contrast enhancement (n = 4). Diffusion-weighted images revealed increased signal intensity at the same location and focally reduced ADC. The ADC values were reduced by 6% to 28% compared with either the normal structure opposite the lesion or normal control. Follow-up MR imaging revealed the complete resolution of the abnormal T2 signal change and swelling in five patients, whereas resolution of the swelling with residual increased T2 signal intensity at the ipsilateral hippocampus was observed in the other two patients. For one of the two patients, hippocampal sclerosis was diagnosed. For the remaining one patient, newly developed increased T2 signal intensity was shown. CONCLUSION: The MR signal changes that occur after generalized tonicoclonic seizure or status epilepticus are transient increase of signal intensity and swelling at the cortical gray matter, subcortical white matter, or hippocampus on periictal T2-weighted and diffusion-weighted images. These findings reflect transient cytotoxic and vasogenic edema induced by seizure. The reversibility and typical location of lesions can help exclude the epileptogenic structural lesions.

MR of mandibular invasion in patients with oral and oropharyngeal malignant neoplasms.

PURPOSE: To investigate whether MR imaging is an accurate means of assessing mandibular invasion in patients with carcinoma. METHODS: We retrospectively studied the MR scans of 22 patients with pathologic or surgical confirmation of mandibular invasion from oral and oropharyngeal cancers. The MR images were blindly analyzed using primary criteria of: (a) cortical breakdown, (b) replacement of bone marrow fat, or (c) gadopentetate dimeglumine enhancement of a mass at the bone marrow defect. Secondary criteria of: (a) contiguous soft-tissue mass, and (b) mass on both sides of the mandibular cortex were also examined. Mandibular invasion was graded as periosteal/cortical, medullary, or no invasion. RESULTS: Primary positive findings of cortical breakdown and abnormal bone marrow signal were highly sensitive (100%) for periosteal/cortical invasion and medullary involvement, respectively. However, a high rate of false-positive studies hampered the MR accuracy, which fell into the 73% to 77% range. A negative MR study was highly predictive, but a positive study was less valuable. Gadolinium enhancement added little to the MR study's accuracy. False-positive studies mainly occurred in the setting of prior irradiation, osteoradionecrosis, and odontogenic infections. CONCLUSIONS: MR imaging is a sensitive method for detecting mandibular invasion but has a low positive predictive value. A negative study virtually excludes cortical/periosteal or bone marrow invasion.

Application of spatial modulation of magnetization to cervical spinal stenosis for evaluation of the hydrodynamic changes occurring in cerebrospinal fluid.

OBJECTIVE: To evaluate the hydrodynamic changes occurring in cerebrospinal fluid (CSF) flow in cervical spinal stenosis using the spatial modulation of magnetization (SPAMM) technique. MATERIALS AND METHODS: Using the SPAMM technique, 44 patients with cervical spinal stenosis and ten healthy volunteers were investigated. The degree of cervical spinal stenosis was rated as low-, intermediate-, or high-grade. Lowgrade stenosis was defined as involving no effacement of the subarachnoid space, intermediate-grade as involving effacement of this space, and high-grade as involving effacement of this space, together with compressive myelopathy. The patterns of SPAMM stripes and CSF velocity were evaluated and compared between each type of spinal stenosis and normal spine. RESULTS: Low-grade stenosis (n = 23) revealed displacement or discontinuity of stripes, while intermediate- (n = 10) and high-grade (n = 11) showed a continuous straight band at the stenotic segment. Among low-grade cases, 12 showed wave separation during the systolic phase. Peak systolic CSF velocity at C4-5 level in these cases was lower than in volunteers (p <.05), but jet-like CSF propulsion was maintained. Among intermediate-grade cases, peak systolic velocity at C1-2 level was lower than in the volunteer group, but the difference was not significant (p >.05). In high-grade stenosis, both diastolic and systolic velocities were significantly lower (p <.05). CONCLUSION: Various hydrodynamic changes occurring in CSF flow in cervical spinal stenosis were demonstrated by the SPAMM technique, and this may be a useful method for evaluating CSF hydrodynamic change in cervical spinal stenosis.