RESUMEN
OBJECTIVE: Recently, a potentially useful diagnostic approach based on MR diffusion-tensor-imaging (DTI) was reported for the estimation of putative functional placenta tissue (PFPT), thus providing direct information about placental function. Yet, the relation between reduced PFPT and the phenomenon of brain-sparing remains unclear. This study aimed to investigate the relation between brain-sparing and reduced PFPT volume, as found in fetuses with intrauterine growth restriction (IUGR). METHODS: A total of 40 consecutive patients with a US-based diagnosis of placental IUGR were examined using fetal MRI. A control group of 78 patients who received fetal MRI, due to non-placental pathologies, was established. A somatic energy index was calculated as IE=1-(Vbrain/Vpfpt) from brain and PFPT volumes measured with DTI in both groups. IE, Vpfpt, and Vbrain were analyzed with respect to the gestational week. RESULTS: Vbrain corrected for gestational weeks was no different between both groups, while Vpfpt was significantly reduced in IUGR patients. IE was significantly different between both groups and indicated a higher Vbrain at a comparable Vpfpt. CONCLUSIONS: Fetuses with IUGR show preserved energetic resources necessary for brain growth. Because IE drops in IUGR more rapidly as pregnancy progresses, depending on Vpfpt, IE could prove useful for estimating fetal well-being.
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Encéfalo/embriología , Encéfalo/patología , Retardo del Crecimiento Fetal/patología , Imagen por Resonancia Magnética/métodos , Placenta/diagnóstico por imagen , Placenta/patología , Adulto , Femenino , Edad Gestacional , Humanos , Tamaño de los Órganos , Embarazo , Diagnóstico Prenatal/métodos , Adulto JovenRESUMEN
BACKGROUND AND PURPOSE: Based on a tight network of stroke units (SUs) and interventional centres, endovascular treatment of acute major intracranial vessel occlusion has been widely implemented in Austria. Documentation of all patients in the nationwide SU registry has thereby become mandatory. METHODS: Demographic, clinical and interventional characteristics of patients who underwent endovascular treatment for acute ischaemic stroke in 11 Austrian interventional centres between 1 October 2013 and 30 September 2014 were analysed. RESULTS: In total, 301 patients (50.5% women; median age 70.5 years; median National Institutes of Health Stroke Scale score 17) were identified.193 patients (64.1%) additionally received intravenous thrombolysis. The most frequent vessel occlusion sites were the M1 segment of the middle cerebral artery (n = 161, 53.5%), the intracranial internal carotid artery (n = 60, 19.9%) and the basilar artery (n = 40, 13.3%). Stent retrievers were used in 235 patients (78.1%) and adequate reperfusion (modified Thrombolysis in Cerebral Infarction scores 2b and 3, median onset to reperfusion time 254 min) was achieved in 242 patients (81.4%). Symptomatic intracranial haemorrhage occurred in 7%. 43.8% of patients (n = 132) had good functional outcome (modified Rankin Scale score 0-2) and the mortality rate was 20.9% (n = 63) after 3 months. Compared to the anterior circulation, vertebrobasilar stroke patients had higher mortality. Patients with secondary hospital transportation had better outcomes after 3 months than in-house treated patients. CONCLUSION: Our results document nationwide favourable outcome and safety rates of endovascular stroke treatment comparable to recent randomized trials. The ability to provide such data and the need to further optimize such an approach also underscore the contribution of respective registries.
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Isquemia Encefálica/terapia , Procedimientos Endovasculares/métodos , Accidente Cerebrovascular/terapia , Trombectomía/métodos , Terapia Trombolítica/métodos , Administración Intravenosa , Anciano , Austria , Isquemia Encefálica/tratamiento farmacológico , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sistema de Registros , Stents , Accidente Cerebrovascular/tratamiento farmacológico , Accidente Cerebrovascular/etiología , Resultado del Tratamiento , Estados UnidosRESUMEN
OBJECTIVES: Intrauterine growth restriction (IUGR) is a diagnostic challenge, since ultrasound fetal biometry (UFB) provides only a 50% detection rate for IUGR. This may be attributable to the fact that UFB does not allow a direct evaluation of functional placental tissue. We hypothesized that direct assessment, using magnetic resonance diffusion tensor imaging (DT-MRI), can provide better detection of IUGR by reliably distinguishing between normal and non-functional placental tissue. METHODS: Patients with normal placenta function (n = 21) and suspected IUGR (n = 14) according to UFB were examined. DT-MRI-based properties of areas of the placenta that were judged to represent normal functional tissue, in normal pregnancies, were used to perform volumetry of the putative functional placental tissue (PFPT) in a control- and an IUGR-group. Fractional anisotropy (FRC), as well as maximum and mean diffusivity were also calculated. RESULTS: PFPT volumetry showed a significant reduction of functional placental tissue in the IUGR group of up to 33%. Analysis of global PFPT, maximum diffusivity, mean diffusivity, and FRC also showed a significant difference. CONCLUSIONS: PFPT volume is dramatically reduced in IUGR. Several DT-MRI parameters suggest an additional placental micro-architecture disturbance in IUGR. PFPT volumetry appears to be a promising tool for improving the detection of IUGR.
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Retardo del Crecimiento Fetal/diagnóstico , Placenta/fisiopatología , Adulto , Femenino , Retardo del Crecimiento Fetal/patología , Edad Gestacional , Humanos , Imagen por Resonancia Magnética/métodos , Tamaño de los Órganos , Placenta/patología , Embarazo , Ultrasonografía PrenatalRESUMEN
BACKGROUND: Recent concepts about cerebrospinal fluid (CSF) circulation in communicating hydrocephalus (CoHy), which is also termed "restricted arterial pulsation hydrocephalus," suggest reduced arterial pulsations of subarachnoid vessels with a smaller amount of CSF shifted in subarachnoid spaces during the early systole. The postulated restriction of subarachnoid arterial pulsations in CoHy should induce a smaller motion artifact and reduced local stream effects in CSF in magnetic resonance (MR) diffusion-weighted imaging (DWI). PURPOSE: To investigate the maximum diffusivity in CSF in patients with and without CoHy using DWI. MATERIAL AND METHODS: 12 patients without CSF circulation disturbances and six cases with proven CoHy were assessed. Diffusion was measured in six non-collinear directions without triggering the arterial pulse wave (scan time 6:45 min, voxel size 2x2x2 mm). Due to expected artifacts, the calculated maximum diffusivity was called apparent diffusivity. Regional high and low apparent diffusivity was assessed in CSF spaces on newly created 3D CSF motion maps. RESULTS: Patients with regular CSF circulation exhibited high apparent diffusivity in CSF in basal subarachnoid spaces, whereas apparent diffusivity was low there in patients with CoHy. CONCLUSION: DWI opens a feasible approach to study CSF motion in the neurocranium. Restricted arterial pulsations seem to be involved in CoHy.
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Líquido Cefalorraquídeo/fisiología , Imagen de Difusión por Resonancia Magnética , Hidrocefalia/fisiopatología , Flujo Pulsátil/fisiología , Adulto , Anciano , Anciano de 80 o más Años , Artefactos , Estudios de Casos y Controles , Femenino , Humanos , Hidrocefalia/patología , Imagenología Tridimensional , Masculino , Persona de Mediana Edad , Espacio Subaracnoideo/patología , Espacio Subaracnoideo/fisiopatologíaRESUMEN
A new technique for fusion and 3D viewing of high resolution magnetic resonance (MR) angiography and morphological MR sequences is reported. Scanning and image fusion was possible within 20 min on a standard 1.5 T MR-scanner. The procedure was successfully performed in 10 consecutive cases with excellent visualization of wall and luminal aspects of the intracranial segments of the internal carotid artery, the vertebrobasilar system and the anterior, middle and posterior cerebral artery.
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Circulación Cerebrovascular , Enfermedades Arteriales Intracraneales/diagnóstico , Angiografía por Resonancia Magnética/métodos , Diagnóstico Diferencial , Humanos , Procesamiento de Imagen Asistido por Computador , Imagenología Tridimensional , Aneurisma IntracranealRESUMEN
Familial hemiplegic migraine (FHM) is a rare inherited autosomal dominant disorder. Migraine aura may last up to several weeks and then resolve without sequel. We report a 21-year-old male with FHM since the age of 3 years. Diffusion-weighted magnetic resonance imaging (DWI), perfusion-MR imaging (P-MRI) and [99mTc] hexamethyl-propyleneamine-oxime-single photon emission tomography (HMPAO-SPECT) were performed on day 2, when he was somnolent with right-sided hemiplegia, on day 9 when a mild hemiparesis was still present and on day 24 after recovery. The right central region showed normal findings in DWI, whereas P-MRI and SPECT revealed hyperperfusion on day 2, less marked on day 9, and normal findings on day 24. In conclusion, this case report indicates for the first time, by means of SPECT, P-MRI and DWI studies, that even extremely long-lasting migraine aura is not associated with cerebral ischaemia. Therefore, it supports the revised International Headache Society criteria where the term 'persistent' aura is proposed.
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Imagen de Difusión por Resonancia Magnética/métodos , Angiografía por Resonancia Magnética/métodos , Migraña con Aura/diagnóstico , Tecnecio , Tomografía Computarizada de Emisión de Fotón Único/métodos , Preescolar , Estudios de Seguimiento , Humanos , Masculino , Migraña con Aura/diagnóstico por imagen , Migraña con Aura/metabolismoRESUMEN
A male patient with bilateral thalamic lesions (medio-ventral nuclei) was investigated. Despite explicit memory impairments his lexical ability was normal. We recorded magnetic field changes (magnetoencephalography, MEG) during the performance of an animate/inanimate discrimination task in which some words where repeated after long delays. Normally, repeated items are classified significantly faster than their first presentations which is accomplished by an unconscious process called priming. The patient did not show any behavioural evidence of priming but the physiological data indicated preservation of this robust form of memory. Brain activation associated with repetitions was attenuated at early stages. The activity difference was posteriorly distributed which is consistent with previous reports about repetition priming. The present study indicated that the bilateral thalamic lesions of our patient disconnected the information processing stream between the primed information and the behavioural response.
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Amnesia/fisiopatología , Memoria , Tálamo/patología , Amnesia/patología , Diencéfalo/patología , Discriminación en Psicología , Humanos , Imagen por Resonancia Magnética , Magnetoencefalografía , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Estimulación Luminosa , Lectura , Reconocimiento en PsicologíaRESUMEN
Neuroradiology should be regarded as a discipline with a strong focus on integral diagnosis of morphology and function of the central nervous system. With perfusion magnetic resonance imaging (P-MRI) and diffusion-weighted magnetic resonance imaging (DWI) the functional micro-structural analysis of the central nervous system has been made possible. So, disease processes may be characterised on a molecular level and P-MRI as well as DWI are now integrated in clinical routine diagnosis to improve therapy planning.
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Encefalopatías/diagnóstico , Encéfalo/irrigación sanguínea , Imagen de Difusión por Resonancia Magnética , Angiografía por Resonancia Magnética , Encefalopatías/fisiopatología , Isquemia Encefálica/diagnóstico , Isquemia Encefálica/fisiopatología , Circulación Colateral/fisiología , Humanos , Flujo Sanguíneo Regional/fisiología , Sensibilidad y EspecificidadRESUMEN
BACKGROUND AND PURPOSE: A quantitative, easily obtained measure of cerebral hemodynamics would be valuable in planning surgical or interventional therapy for patients with stenotic or occlusive disease of the carotid artery. We evaluated the recently introduced standardized time-to-peak variable (stdTTP), obtained with dynamic susceptibility contrast-enhanced MR (DSC-MR) imaging, in different states of stenotic/occlusive carotid artery disease. METHODS: We examined 24 patients with unilateral, high-grade stenosis (85%-95%) of one internal carotid artery (ICA) and 10 patients with stenosis (85%-95%) of one ICA and occlusion of the contralateral ICA. Mean stdTTP was evaluated in the central vascular territories of the anterior, middle, and posterior cerebral arteries and the anterior and posterior border zones and compared with the mean stdTTP values from 36 cerebral hemispheres without hemodynamic impairment. RESULTS: Patients showed no significant prolongation of stdTTP in the central vascular territories compared with the reference group, whereas significant prolongations of stdTTP were measured in the anterior and posterior border zones in patients with ICA disease (ANOVA, P <.05) and were most prominent in higher grades of carotid disease. Hemispheres with hemodynamic impairment always showed a stdTTP > 3.5 s in the border zones. CONCLUSION: The StdTTP quantitatively describes the hemodynamic impairment in cerebral hemispheres supplied by a stenosed or occluded ICA. An stdTTP value of > 3.5 s, as has been postulated, seems to point out hemodynamic impairment.
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Estenosis Carotídea/diagnóstico , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Anciano , Velocidad del Flujo Sanguíneo/fisiología , Encéfalo/irrigación sanguínea , Arteria Carótida Interna/patología , Arteria Carótida Interna/fisiopatología , Estenosis Carotídea/fisiopatología , Estenosis Carotídea/cirugía , Medios de Contraste , Imagen Eco-Planar , Femenino , Gadolinio DTPA , Hemodinámica/fisiología , Humanos , Imagenología Tridimensional , Angiografía por Resonancia Magnética , Masculino , Persona de Mediana Edad , Valores de Referencia , Flujo Sanguíneo Regional/fisiología , Sensibilidad y EspecificidadRESUMEN
Until recently, the most appropriate technique of intubating a patient with a cervical spine injury has been the subject of debate. Tracheal intubation by means of the intubating laryngeal mask (Fastrach), a modified conventional laryngeal mask airway, seems to require less neck manipulation. The aim of this study was to compare the excursion of the upper cervical spine during tracheal intubation using direct laryngoscopy with that during intubation via the laryngeal mask (Fastrach), by examination of lateral cervical spine radiographs in healthy young patients. The intubating laryngeal mask (Fastrach) caused less extension (at C1-2 and C2-3) than intubation by direct laryngoscopy. Direct laryngoscopy is still the fastest method to secure an airway provided no intubating difficulties are present. However, in trauma patients requiring rapid sequence induction and in whom cervical spine movement is limited or undesirable, the intubating laryngeal mask (Fastrach) is a safe and fast method by which to secure the airway.
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Vértebras Cervicales/lesiones , Vértebras Cervicales/fisiología , Intubación Intratraqueal/métodos , Laringoscopía , Movimiento , Adulto , Vértebras Cervicales/diagnóstico por imagen , Femenino , Humanos , Máscaras Laríngeas , Masculino , Persona de Mediana Edad , Estudios Prospectivos , RadiografíaRESUMEN
Common causes to consultate a neuroradiologist in case of emergencies are trauma, brain infarction, or intracranial bleeding. Patients with brain infarction need a rapid assessment of the potentially nonnecrotic area within the ischaemic lesion. If haemorrhage, mostly occurring in the form of subarachnoid bleeding, is suspected, the source of bleeding has to be detected. With cranial computed tomography (CT) a thorough evaluation and staging of ischaemic stroke is possible with respect to thrombolysis. To detect irreversible damage of brain tissue, a combined perfusion-diffusion MRI should be performed.
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Lesiones Encefálicas/diagnóstico por imagen , Hemorragias Intracraneales/diagnóstico por imagen , Neurorradiografía/métodos , Accidente Cerebrovascular/etiología , Infarto Encefálico/diagnóstico por imagen , Isquemia Encefálica/diagnóstico por imagen , Diagnóstico Diferencial , Humanos , Angiografía por Resonancia Magnética , Imagen por Resonancia Magnética , Hemorragia Subaracnoidea/diagnóstico por imagen , Tomografía Computarizada por Rayos XRESUMEN
Carotid endarterectomy (CEA) is proven to be beneficial in symptomatic patients with high-grade carotid stenosis (70% to 99%; residual lumen as a percentage of the normal distal internal carotid artery) on condition that the peri-operative risk for mortality and morbidity is less than 6%. A minority of the "leading experts" in North America (48%) and Western Europe (28%) recommends carotid endarterectomy in asymptomatic patients in general. Most experts suggest to perform surgery only in asymptomatic patients who are at risk for carotid occlusion in the near future or embolism. At its present state, angioplasty and stenting is an experimental although promising technique which will have to be compared to carotid endarterectomy. Criteria for duplex grading of internal carotid stenosis have been established and systematically validated to results of angiography. Pre-surgical use of angiography will more and more be restricted to selected patients in whom the results of duplex sonography remain inconclusive. The detection of microemboli with transcranial doppler sonography seems to be of particular importance before and during carotid angioplasty and stenting.
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Angioplastia de Balón , Trombosis de las Arterias Carótidas/diagnóstico , Estenosis Carotídea/terapia , Endarterectomía Carotidea , Estenosis Carotídea/diagnóstico , Estenosis Carotídea/fisiopatología , Hemodinámica , Humanos , Monitoreo Fisiológico , Pronóstico , Ensayos Clínicos Controlados Aleatorios como Asunto , StentsRESUMEN
BACKGROUND AND PURPOSE: Perfusion MR imaging, performed as dynamic-susceptibility contrast-enhanced MR imaging, is sensitive to hemodynamic risks for patients with cerebrovascular disease. We sought to define a quantitative parameter for perfusion MR imaging, which shows brain areas at hemodynamic risk and enables direct comparison of different perfusion MR imaging examinations. METHODS: A new standardization procedure for the time-to-peak (TTP) parameter, standardized time to peak (stdTTP), was introduced. The stdTTP automatically calculates a time offset correlated to the earliest enhancing voxels in a section and rescales all TTP values accordingly. Because of a close relation between this offset and stdTTP of early enhancing voxels in central vascular territories (CVTs), stdTTP provides an estimate of the bolus run time between CVTs and related border zones (BZs). The stdTTP in CVTs and BZs was measured in 11 patients without hemodynamic impairment by using high temporal resolution dynamic-susceptibility contrast-enhanced perfusion MR imaging. RESULTS: An excellent comparability of different dynamic susceptibility contrast-enhanced MR imaging studies was found. The stdTTP in CVTs was 0.4 +/- 0.5 s (minimum, 0 s; maximum, 1.3 s) for the anterior, 0.5 +/- 0.3 s (minimum, 0 s; maximum, 1.0 s) for the middle, and 1.4 +/- 0.5 s (minimum, 0.4 s; maximum, 2.4 s) for the posterior cerebral artery. In the anterior BZ, stdTTP was 2.3 +/- 0.4 s (minimum, 1.6 s; maximum, 3.2 s), and in the posterior BZ, stdTTP was 2.8 +/- 0.4 s (minimum, 2.0 s; maximum, 3.4 s). CONCLUSION: The results suggest a limit for stdTTP of approximately 3.5 s in the anterior and posterior BZs. The stdTTP could serve as a quantitative measure for the hemodynamic risk assessment of patients with cerebrovascular disease. Because stdTTP can be directly derived from the measured curves, the hemodynamic situation of a patient can be judged with a minimum of computational effort.
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Encéfalo/irrigación sanguínea , Medios de Contraste , Epilepsia/diagnóstico , Hemodinámica/fisiología , Aumento de la Imagen , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética/métodos , Adulto , Barrera Hematoencefálica/fisiología , Epilepsia/fisiopatología , Femenino , Humanos , Masculino , Valores de Referencia , Flujo Sanguíneo Regional/fisiologíaRESUMEN
(99m)Tc-Sestamibi (MIBI) has been successfully applied in recurrent glioblastoma. The aim of this study was to evaluate the incremental diagnostic information of MIBI as a tumor-avid radiopharmaceutical compared with (99m)Tc-pertechnetate ((99m)Tc) as sole indicator of the integrity of the blood-brain barrier. Twenty-five patients with confirmed recurrent brain tumors were included. MIBI SPET was performed 10 min after injection of 555 MBq MIBI intravenously with a triple-headed gamma camera equipped with LE-UHR-PAR collimators over 360 degrees (3 degrees /step) and stored in a 128(2) matrix. Identical acquisition parameters were used for (99m)Tc SPET, which was acquired 3 h after injection of 740 MBq (99m)Tc. Normalized tumor uptake (NU) was calculated from attenuation-corrected transaxial slices. In addition, tumor/plexus, tumor/nasopharynx, and tumor/parotid gland ratios were assessed in both studies. No statistically significant differences were detected for the mean NU of tumor tissue with MIBI (0.26 +/- 0.10) and (99m)Tc (0.39 +/- 0. 33) and for the tumor/nasopharynx and tumor/parotid gland ratios; only the tumor/plexus ratio was significantly higher for (99m)Tc than for MIBI (p < 0.05). In conclusion, our data indicate that MIBI scintigraphy in brain tumors at 10 min postinjection reveals no additional visual information over that provided by the conventional (99m)Tc-pertechnetate brain scan, and in addition, tracer retention reflects primarily blood-brain barrier damage.
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Barrera Hematoencefálica , Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/metabolismo , Glioblastoma/diagnóstico por imagen , Oligodendroglioma/diagnóstico por imagen , Radiofármacos , Tecnecio Tc 99m Sestamibi , Adulto , Femenino , Glioblastoma/metabolismo , Humanos , Masculino , Persona de Mediana Edad , Oligodendroglioma/metabolismo , Cintigrafía , Pertecnetato de Sodio Tc 99mRESUMEN
Local intra-arterial lysis using recombinant tissue plasminogen activator (rTPA) was performed in a 6 and 2/3-year-old patient with major cardioembolic ischemic stroke 48 hours after intracardiac surgery. Selective application of 2.5 mg rTPA (0.11 mg/kg body weight) resulted in recanalization of the occluded cerebral vasculature with good neurologic recovery.
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Infarto de la Arteria Cerebral Media/terapia , Terapia Trombolítica , Activador de Tejido Plasminógeno/administración & dosificación , Procedimientos Quirúrgicos Cardíacos/efectos adversos , Angiografía Cerebral , Niño , Femenino , Humanos , Infarto de la Arteria Cerebral Media/diagnóstico , Infarto de la Arteria Cerebral Media/etiología , Inyecciones Intralesiones , Imagen por Resonancia Magnética , Complicaciones Posoperatorias/etiología , Complicaciones Posoperatorias/terapia , Tomografía Computarizada por Rayos X , Resultado del TratamientoRESUMEN
UNLABELLED: The three-in-one technique of simultaneously blocking the femoral, the lateral femoral cutaneous (LFC), and the obturator nerves by a single injection of a local anesthetic was first described in 1973, and it was suggested that the underlying mechanism was one of cephalad spread resulting in a blockade of the lumbar plexus. Today, the technique is widely used in surgery and pain management of the lower limb. Many investigators have, however, reported suboptimal analgesia levels, particularly in the obturator nerve. The purpose of this prospective study was to trace the distribution of a local anesthetic during a three-in-one block by means of magnetic resonance imaging (MRI). Seven patients scheduled for surgery of the lower limb were analyzed with the aid of a primary MRI and then received three-in-one blocks using 30 mL of bupivacaine 0.5% under the guidance of a nerve stimulator. A secondary MRI was performed to determine the distribution pattern of the local anesthetic. It emerged that the local anesthetic blocks the femoral nerve directly, the LFC nerve through lateral spread, and the anterior branch of the obturator nerve by slightly spreading in a medial direction. No involvement of the proximal and posterior portions of the obturator nerve was observed, nor was there any cephalad spread that could have resulted in a lumbar plexus blockade. We therefore conclude that the basis of the three-in-one block is confined to lateral, medial, and caudal spread of the local anesthetic, which effectively blocks the femoral and LFC nerves, as well as the distal anterior branch of the obturator nerve. IMPLICATIONS: We demonstrate by using magnetic resonance imaging that the mechanism of a three-in-one block is one of lateral, caudal, and slight medial spread of a local anesthetic with subsequent blockade of the femoral, the lateral femoral cutaneous, and the anterior branch of the obturator nerves. It does not involve cephalad spread of the local anesthetic with blockade of the lumbar plexus.
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Anestésicos Locales/farmacocinética , Bloqueo Nervioso , Anciano , Anciano de 80 o más Años , Anestésicos Locales/administración & dosificación , Femenino , Nervio Femoral , Humanos , Pierna/anatomía & histología , Imagen por Resonancia Magnética , Masculino , Nervio Obturador , Dolor Postoperatorio/tratamiento farmacológico , Heridas y Lesiones/cirugíaRESUMEN
BACKGROUND AND PURPOSE: On cross-sectional and panoramic reformatted images from axial (dental) CT scans of the mandible it may be difficult to identify the inferior alveolar neurovascular bundle (IANB) in patients lacking a clear-cut bony delimitation of the mandibular canal. Dental MR images are comparable to dental CT scans, which directly show the IANB; however, measurements of length may not be reliable owing to susceptibility artifacts and field inhomogeneities in the oral cavity. Therefore, the accuracy of length measurements on dental MR images was compared with that on dental CT scans and direct osteometry. METHODS: Dental T1-weighted MR imaging using a high-resolution turbo gradient-echo sequence and dental CT were performed in six anatomic specimens. The axial scans were reformatted as panoramic and cross-sectional reconstructions on a workstation and characteristic cross sections were obtained from all mandibles. The longest axis in the bucco-lingual and apico-basal directions, the distances from the top of the mandibular canal to the top of the alveolar ridge and from the bottom of the mandibular canal to the base of the mandible, and the diameter of the bone cortex at the alveolar ridge were measured with direct osteometry on the cross sections and compared with measurements on corresponding MR and CT reformatted images. RESULTS: The correlation between direct osteometry and dental MR and CT was strong, except for the bone cortex diameter at the top of the alveolar ridge, where only a moderate correlation was found. Means of comparable length measurements were not significantly different among the three methods. CONCLUSION: The accuracy of length measurements in the jaw bones obtained using dental MR is comparable to that of dental CT and is not significantly different from direct osteometry. Thus, dental MR is a potential alternative to CT for dental imaging.
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Imagen por Resonancia Magnética , Mandíbula/anatomía & histología , Proceso Alveolar/anatomía & histología , Humanos , Procesamiento de Imagen Asistido por Computador , Técnicas In Vitro , Mandíbula/diagnóstico por imagen , Radiografía Panorámica , Tomografía Computarizada por Rayos XRESUMEN
PURPOSE: To demonstrate the usefulness of Dental-MRT for imaging of anatomic and pathologic conditions of the mandible and maxilla. METHODS: Seven healthy volunteers, 5 patients with pulpitis, 9 patients with dentigerous cysts, 5 patients after tooth transplantation and 12 patients with atrophic mandibles were evaluated. Studies of the jaws using axial T1- and T2-weighted gradient echo and spin echo sequences in 2D and 3D technique have been to performed. The acquired images were reconstructed with a standard dental software package on a workstation as panoramic and cross sectional views of the mandible or maxilla. RESULTS: The entire maxilla and mandibula, teeth, dental pulp and the content of the mandibular canal were well depicted. Patients with inflammatory disease of the pulp chamber demonstrate bone marrow edema in the periapical region. Dentigerous cysts and their relation to the surrounding structures are clearly shown. After contrast media application marked enhancement of the dental pulp can be found. CONCLUSION: Dental-MRT provides a valuable tool for visualization and detection of dental diseases.
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Diagnóstico por Imagen/métodos , Imagen por Resonancia Magnética , Enfermedades de la Boca/diagnóstico , Tomografía Computarizada por Rayos X , Enfermedades Dentales/diagnóstico , Humanos , Enfermedades Maxilomandibulares/diagnóstico , Mandíbula/diagnóstico por imagen , Maxilar/diagnóstico por imagen , Quistes Odontogénicos/diagnóstico , Pulpitis/diagnóstico , Anomalías Dentarias/diagnósticoRESUMEN
Within certain limits the vascularity of cerebral gliomas correlates with dysplasia. Xenon CT and perfusion MRI can be used to investigate tumor vascularity. Using an optimized wash in/out protocol with inhalation of 30% xenon gas, xenon CT was performed and regional cerebral blood flow (rCBF) and blood/tissue partition coefficient (lambda) calculated. Furthermore, perfusion MRI was performed using a dynamic T2*w EPI sequence with intravenous administration of Gd-DTPA. The relative regional cerebral blood volume, arrival time, time to peak and mean transit time were calculated. Both modalities were used in patients with supratentorial gliomas and compared with conventional contrast-enhanced MRI (ceMRI). Calculation of regional cerebral blood flow, as compared to ceMRI, did not contribute to the diagnostic approach of tumor dysplasia. Tumour vascularity was better estimated by measurement of lambda. Measurement of relative regional cerebral blood volume also correlated with tumor vascularity. Mainly the possibility of direct quantification of the Xe-CT data was advantagenous compared to perfusion MRI, and the XeCT data could be interpreted more clearly. Further upgrades of the technical equipment of MR as well as upgrades of available software will increase the applicability of perfusion MRI. However, both modalities offer a more precise investigation of tumor vascularization compared to ceMRI since potential dysplastic alteration may be detected earlier, which will be advantageous for planning bioptical approach of such tumours.