ABSTRACT
PURPOSE: This study evaluated the sensitivity of a 3.0-Tesla (T) magnetic resonance imaging (MRI) in measuring cerebral phenylalanine using proton magnetic resonance spectroscopy and in assessing MR-documented white-matter changes by means of diffusion studies (diffusion-weighted imaging, apparent diffusion coefficient map; diffusion tensor imaging) in patients with phenylketonuria. MATERIALS AND METHODS: Thirty-two patients with the classical clinical and biochemical deficits of phenylketonuria underwent biochemical (blood phenylalanine), genotypic (phenylalanine hydroxylase gene) and radiological investigation by means of MRI, proton magnetic resonance spectroscopy and diffusion magnetic resonance imaging with a 3.0-T scanner. RESULTS: Periventricular and subcortical white-matter changes were detected on all MR scans. In 29/32 patients, proton magnetic resonance spectroscopy easily documented abnormal signal elevation at 7.36 ppm, corresponding to phenylalanine, despite its low concentration. Phenylalanine signal amplitude relative to the creatine/phosphocreatine signal increased linearly with blood phenylalanine values (r 0.7067; p<0.001). Diffusion MRI demonstrated hyperintensity in the areas exhibiting MRI changes as well as decreased apparent diffusion coefficient values, but fractional anisotropy indices were normal. CONCLUSIONS: The high signal, together with better spectral, spatial, contrast and temporal resolution, makes the 3.0-T MR the most suitable technique in the study of the phenylketonuria. In particular, the multimodal approach with MRI, proton magnetic resonance spectroscopy and diffusion magnetic resonance imaging can provide more information than previous studies performed with low-field systems.
Subject(s)
Brain/pathology , Diffusion Magnetic Resonance Imaging , Magnetic Resonance Imaging/methods , Magnetic Resonance Spectroscopy , Phenylketonurias/diagnosis , Adolescent , Adult , Child , Female , Humans , Male , Phenylketonurias/pathology , Sensitivity and SpecificityABSTRACT
PURPOSE: This study was performed to clarify the role of perfusion-weighted imaging (PWI) at 3 Tesla in the characterisation of haemodynamic heterogeneity within gliomas and surrounding tissues and in the differentiation of high-grade from low-grade gliomas. MATERIALS AND METHODS: We examined 36 patients with histologically verified gliomas (25 with high-grade and 11 with low-grade gliomas). PWI was performed by first-pass gadopentetate dimeglumine T2*-weighted echo-planar images, and cerebral blood volume (CBV) maps were computed with a nondiffusible tracer model. Relative CBV (rCBV) was calculated by dividing CBV in pathological areas by that in contralateral white matter. RESULTS: In high-grade gliomas, rCBV were markedly increased in mass [mean+/-standard deviation (SD), 4.3+/-1.2] and margins (4.0+/-1.1) and reduced in necrotic areas (0.3+/-0.3). Oedematous-appearing areas were divided in two groups according to signal intensity on T2-weighted images: tumour with lower (nearly isointense to grey matter) and oedema with higher (scarcely isointense to cerebrospinal fluid) signal intensity. Tumour showed significantly higher rCBV than did oedema (1.8+/-0.5 vs. 0.5+/-0.2; p<0.001) areas. In low-grade gliomas, mass (2.0+/-1.5) and margin (2.2+/-1.2) rCBV were significantly lower than in high-grade gliomas (p<0.001). CONCLUSIONS: Three-Tesla PWI helps to distinguish necrosis from tumour mass, infiltrating tumour from oedema and high-grade from low-grade gliomas. It enhances the magnetic resonance (MR) assessment of cerebral gliomas and provides useful information for planning surgical and radiation treatment.
Subject(s)
Brain Neoplasms/diagnosis , Glioma/diagnosis , Image Processing, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Adult , Aged , Astrocytoma/diagnosis , Blood Volume/physiology , Brain Edema/diagnosis , Cerebrovascular Circulation/physiology , Contrast Media , Diagnosis, Differential , Echo-Planar Imaging/methods , Female , Gadolinium DTPA , Ganglioglioma/diagnosis , Glioblastoma/diagnosis , Humans , Image Enhancement/methods , Male , Middle Aged , Necrosis , Oligodendroglioma/diagnosis , Retrospective StudiesABSTRACT
The aim of this paper is to illustrate the technical, methodological and diagnostic features of functional imaging (comprising spectroscopy, diffusion, perfusion and cortical activation techniques) and its principal neuroradiological applications on the basis of the experience gained by the authors in the 5 years since the installation of a high-field magnetic resonance (MR) magnet. These MR techniques are particularly effective at 3.0 Tesla (T) owing to their high signal, resolution and sensitivity, reduced scanning times and overall improved diagnostic ability. In particular, the high-field strength enhances spectroscopic analysis due to a greater signal-to-noise ratio (SNR) and improved spectral, space and time resolution, resulting in the ability to obtain high-resolution spectroscopic studies not only of the more common metabolites, but also--and especially--of those which, due to their smaller concentrations, are difficult to detect using 1.5-T systems. All of these advantages can be obtained with reduced acquisition times. In diffusion studies, the high-field strength results in greater SNR, because 3.0-T magnets enable increased spatial resolution, which enhances accuracy. They also allow exploration in greater detail of more complex phenomena (such as diffusion tensor and tractography), which are not clearly depicted on 1.5-T systems. The most common perfusion study (with intravenous injection of a contrast agent) benefits from the greater SNR and higher magnetic susceptibility by achieving dramatically improved signal changes, and thus greater reliability, using smaller doses of contrast agent. Functional MR imaging (fMRI) is without doubt the modality in which high-field strength has had the greatest impact. Images acquired with the blood-oxygen-level-dependent (BOLD) technique benefit from the greater SNR afforded by 3.0-T magnets and from their stronger magnetic susceptibility effects, providing higher signal and spatial resolution. This enhances reliability of the localisation of brain functions, making it possible to map additional areas, even in the millimetre and submillimetre scale. The data presented and results obtained to date show that 3.0-T morphofunctional imaging can become the standard for high-resolution investigation of brain disease.
Subject(s)
Brain/physiology , Diffusion Magnetic Resonance Imaging/methods , Image Processing, Computer-Assisted/methods , Magnetic Resonance Imaging/methods , Magnetic Resonance Spectroscopy/methods , Artifacts , Aspartic Acid/analogs & derivatives , Aspartic Acid/analysis , Brain Diseases/diagnosis , Brain Diseases/physiopathology , Brain Neoplasms/diagnosis , Cerebral Arteries/physiology , Cerebral Cortex/physiology , Choline/analysis , Contrast Media/administration & dosage , Creatine/analysis , Humans , Image Enhancement/methods , Oxygen/blood , Time Factors , gamma-Aminobutyric Acid/analysisABSTRACT
Ever since the introduction of magnetic resonance (MR), imaging with 1.5 Tesla (T) has been considered the gold standard for the study of all areas of the body. Until not long ago, higher-field MR equipment was exclusively employed for research, not for clinical use. More recently, the introduction of 3.0-T MR machines for new and more sophisticated clinical applications has resulted in important benefits, especially in neuroradiology. Indeed, their high gradient power and field intensity (3.0 T) allow adjunctive and more advanced diagnostic methodologies to be performed with excellent resolution in a fraction of the acquisition time required with earlier machines. The purpose of this paper is to illustrate the distinctive semeiological characteristics of 3.0-T morphological and angiographic brain imaging compared with lower-field systems and highlight the respective advantages and drawbacks based on the experience gained in the first 5 years from the installation of a 3.0-T magnet.
Subject(s)
Brain Diseases/diagnosis , Brain/anatomy & histology , Image Processing, Computer-Assisted/methods , Magnetic Resonance Angiography/methods , Magnetic Resonance Imaging/methods , Artifacts , Brain/blood supply , Cerebral Hemorrhage/diagnosis , Cerebrospinal Fluid , Contrast Media/administration & dosage , Gadolinium/administration & dosage , Humans , Image Enhancement/methods , Image Processing, Computer-Assisted/instrumentation , Intracranial Arteriovenous Malformations/diagnosis , Magnetic Resonance Angiography/instrumentation , Magnetic Resonance Imaging/instrumentation , Time FactorsABSTRACT
OBJECTIVE: To gain insights into the nature and pathogenesis of white matter (WM) abnormalities in PKU. METHODS: Thirty-two patients with phenylalanine hydroxylase deficiency (21 with early and 11 with late diagnosis and treatment) and 30 healthy controls underwent an integrated clinical, neuroimaging (3.0 T MRI, diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI)) and neurochemical (1H MRS) investigation. RESULTS: All patients had white matter abnormalities on T2-weighted (T2W) and fluid-attenuated inversion recovery (FLAIR) scans; parietal white was consistently affected, followed by occipital, frontal and temporal white matter. T1-weighted hypointense alterations were also found in 8 of 32 patients. DWI hyperintense areas overlapped with those detected on T2W/FLAIR. The apparent diffusion coefficient (ADC) was reduced and correlated inversely with severity of white matter involvement. Fractional anisotropy index, eigenvalues lambda(min), lambda(middle), lambda(max) obtained from DTI data, and the principal brain metabolites assessed by 1H MRS (except brain phenylalanine (Phe)) were normal. Brain Phe peak was detected in all but two subjects. Brain and blood Phe were strictly associated. Blood Phe at the diagnosis, patient's age, and concurrent brain Phe independently influence white matter alteration (as expressed by conventional MRI or ADC values). CONCLUSIONS: (a) MRI abnormalities in phenylketonuria are the result of a distinctive alteration of white matter suggesting the intracellular accumulation of a hydrophilic metabolite, which leaves unaffected white matter architecture and structure. (b) White matter abnormalities do not seem to reflect the mechanisms involved in the derangement of mental development in PKU. (c) Our data do not support the usefulness of conventional brain MRI examination in the clinical monitoring of phenylketonuria patients.
Subject(s)
Brain/pathology , Diffusion Magnetic Resonance Imaging , Magnetic Resonance Spectroscopy , Phenylketonurias/diagnosis , Adolescent , Adult , Brain/metabolism , Child , Female , Humans , Male , Middle Aged , Phenylalanine/blood , Phenylalanine/metabolism , Phenylketonurias/blood , Phenylketonurias/metabolism , Severity of Illness IndexABSTRACT
Recent advances in magnetic resonance imaging (MRI) have allowed the evaluation of metabolic, diffusion and hemodynamic features of malignant gliomas. The aim of this study was to evaluate whether such information provided useful, complementary information to conventional MRI for improving the evaluation of glioblastoma extent. Ten patients with glioblastoma multiforme underwent conventional MRI, proton MR spectroscopic imaging (1H-MRSI), perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI). Metabolite signals, including normalized choline, N-acetylaspartate, creatine and lactate/lipids, were obtained by 1H-MRSI; apparent diffusion coefficient (ADC) by DWI; and relative cerebral blood volume (rCBV) by PWI. In edematous-appearing areas, 3 multiparametric patterns were identified: infiltrating tumor, with abnormal metabolite ratios, lower ADC and higher rCBV; pure edema, with normal metabolite ratios, higher ADC and lower rCBV; and tumor-infiltrated edema, with abnormal metabolite ratios and intermediate ADC and rCBV. In normal-appearing areas, 2 multiparametric patterns were identified: tumor-infiltrated tissue, with abnormal metabolite ratios and higher rCBV; and normal tissue, with normal MR parameters. The combination of 1H-MRSI, DWI and PWI features contributed to delineation of glioblastomas, offering information not available with conventional MRI. This approach may enhance the assessment of brain gliomas, providing useful information for guiding stereotactic biopsies, surgical resection and radiation treatment.
Subject(s)
Brain Neoplasms/diagnosis , Diffusion Magnetic Resonance Imaging/methods , Glioblastoma/diagnosis , Magnetic Resonance Spectroscopy/methods , Edema/etiology , Female , Humans , Male , Middle Aged , PerfusionABSTRACT
Brain magnetic resonance imaging (MRI) studies in migraine patients have demonstrated lesions consisting of focal regions of increased signal intensity within the white matter. Antiphospholipid antibodies are known to have a role in many diseases including migraine. The aim of the present study was to ascertain the relationship between MRI-visualized cerebral focal hyperintense lesions and serum antiphospholipid antibody levels, as well as blood coagulation parameters in migraine patients. One hundred and two (77 females, 25 males, mean age 33.8 +/- 11.1) consecutive migraine patients and a control group of 94 (70 females, 24 males, mean age 33.2 +/- 10.8) healthy subjects were enrolled. All individuals underwent brain MRI. Complete blood examinations, autoantibodies, antiphospholipids antibodies including anticardiolipin and lupus anticoagulant (aCL, LAC), antithrombin III, Protein C and S serum levels were ascertained in the subjects who presented white matter lesions on MRI. Twenty-seven (26.4%) migraine patients and six (6.3%) healthy subjects in the control group showed focal regions of increased intensity signal within cerebral white matter (odds ratio 5.3, 95% CI: 1.98-16.36). In migraine patients with white matter lesions, antiphospholipid antibodies were not detected and serum levels of antithrombin III, and proteins C and S were normal. White matter lesions in migraine patients are fairly common. This finding is not associated with antiphospholipid antibodies or abnormal coagulation parameters. The significance of such lesions at present remains unclear.
Subject(s)
Antibodies, Antiphospholipid/blood , Blood Coagulation , Brain/immunology , Brain/pathology , Migraine Disorders/immunology , Migraine Disorders/pathology , Adult , Female , Humans , Immunoglobulin D/blood , Informed Consent , Magnetic Resonance Imaging , Male , Migraine Disorders/blood , Patient Selection , Reference ValuesABSTRACT
The radiologic modality that most likely provides the imaging information needed in a patient suspected of having a brain tumors is magnetic resonance imaging. A brain tumors can be reliably ruled out, if the standard magnetic resonance examination is performed properly and experts interpret the results as negative for tumor. In this paper we will illustrate morphological aspects of low-grade supratentorial neoplasms, including tumors of neuroepithelial tissue, such as low-grade diffuse fibrillary astrocytomas, and circumscribed astrocytic lesions (pilocytic astrocytoma, pleomorphic xantoastrocytoma and subependymal giant cell astrocytoma). Then the main practical applications of functional imaging in neurosurgery will be also debated.
Subject(s)
Glioma/diagnostic imaging , Glioma/pathology , Magnetic Resonance Imaging , Supratentorial Neoplasms/diagnostic imaging , Supratentorial Neoplasms/pathology , Brain/diagnostic imaging , Brain/pathology , Humans , RadiographyABSTRACT
Proton magnetic resonance spectroscopy (1H-MRS) of the brain reveals specific biochemical information about cerebral metabolites, which may support clinical diagnoses and enhance the understanding of neurological disorders. The advantages of performing 1H-MRS at higher field strengths include better signal to noise ratio (SNR) and increased spectral, spatial and temporal resolution, allowing the acquisition of high quality, easily quantifiable spectra in acceptable imaging times. In addition to improved measurement precision of N-acetylaspartate, choline, creatine and myo-inositol, high-field systems allow the high-resolution measurement of other metabolites, such as glutamate, glutamine, gamma-aminobutyric acid, scyllo-inositol, aspartate, taurine, N-acetylaspartylglutamate, glucose and branched amino acids, thus extending the range of metabolic information. However, these advantages may be hampered by intrinsic field-dependent technical difficulties, such as decreased T2 signal, chemical shift dispersion errors, J-modulation anomalies, increased magnetic susceptibility, eddy current artifacts, limitations in the design of homogeneous and sensitive radiofrequency (RF) coils, magnetic field instability and safety issues. Several studies demonstrated that these limitations could be overcome, suggesting that the appropriate optimization of high-field 1H-MRS would expand the application in the fields of clinical research and diagnostic routine.
Subject(s)
Brain/metabolism , Magnetic Resonance Spectroscopy , Algorithms , Humans , Magnetic Resonance Spectroscopy/adverse effects , Magnetic Resonance Spectroscopy/methods , ProtonsABSTRACT
Gastric cancer is often diagnosed in middle-aged patients undergoing upper gastrointestinal endoscopy for abdominal complaints or constitutional symptoms, such as dyspepsia, vomiting or anorexia, weight loss, anemia, jaundice, and ascites. Sometimes, all of these symptoms may be absent, and gastric cancer is diagnosed after detection of metastases to target organs, such as the liver or lung. In a few rare cases, however, even these metastatic localizations may be absent, and clinical signs are only represented by atypical symptoms caused by neurologic metastatic involvement. We report an exceptionally rare case of gastric cancer in which the only presenting symptoms were headache and dizziness caused by a single cerebellar metastasis.
Subject(s)
Carcinoma, Signet Ring Cell/secondary , Cerebellar Neoplasms/secondary , Stomach Neoplasms/diagnosis , Carcinoma, Signet Ring Cell/diagnosis , Carcinoma, Signet Ring Cell/pathology , Cerebellar Neoplasms/diagnosis , Cerebellar Neoplasms/pathology , Cerebellum/pathology , Diagnosis, Differential , Gastroscopy , Humans , Male , Middle Aged , Stomach/pathology , Stomach Neoplasms/pathologyABSTRACT
PURPOSE: To determine sensitivity, specificity and diagnostic accuracy of contrast-enhanced magnetic resonance angiography (CE MRA) compared to digital subtraction angiography (DSA) in the study of carotid stenosis. METHODS AND MATERIAL: We studied 23 patients with suspected cerebro-vascular insufficiency by carotid stenosis. Diagnostic examinations by means of CE MRA and DSA were carried out within 24 hours of each other. A 1.5 T superconductive magnet (Signa-General Electric) was used for CE MRA. This technique was performed using a fast spoiled gradient echo recalled (SPGR) sequence acquired in coronal plane 13 sec after injection of contrast medium. Imaging parameters were: TR/TE/FA 8 msec/1 msec/60 degrees, matrix 256 x 128, 1 excitation, FOV 18 x 13 cm, 28 slices per slab, slice thickness of 1 mm, acquisition time of 32 sec. The post-processing was performed using maximum intensity projection (MIP) and targeted MIP. For DSA examinations a Politron 1000 VR unit (Siemens) was used. RESULTS: In the identification and quantification of lesions, CE MRA showed values of 100%. In particular, in comparison to DSA, CE MRA was accurate in diagnosing all true negative and positive cases. The location of stenosis evaluated with CE MRA agreed in all cases with DSA. CONCLUSION: In our experience CE MRA proved to be a very valuable technique in diagnosing carotid stenosis, showing the same diagnostic accuracy as DSA. In this way CE MRA appears to be a substantial alternative technique to conventional MRA and other non-invasive diagnostic methods.
Subject(s)
Angiography, Digital Subtraction , Carotid Stenosis/diagnosis , Magnetic Resonance Angiography/methods , Radiographic Image Enhancement/methods , Aged , Contrast Media , Female , Humans , Male , Middle AgedABSTRACT
PURPOSE: To compare the accuracy of three different magnetic resonance angiography (MRA) techniques for studying steno-occlusive disease of carotid arteries. METHODS: 64 patients were evaluated with three MRA techniques- three-dimensional (3D) time-of-flight (TOF), two-dimensional (2D) TOF, and 3D Phase-Contrast (PC); the acquisition was in the axial plane, the volume included the carotid bifurcation. Digital subtraction angiography (DSA) was considered the 'gold standard'. The MRA images were reprojected with a maximum intensity pixel ray-tracing (MIP) algorithm. The three MRA techniques were blindly graded as normal, mildly stenotic (0-29%), moderately stenotic (30-49%), severely stenotic (70-99%), or occluded. RESULTS: DSA provided 128 diagnostic judgments: 92 were negatives and 36 positives. 2D TOF was in agreement with angiography in 116 of 128 cases (90%), but overestimated the results in seven cases and underestimated in five cases. 3D TOF agreed with angiography in 125 of 128 cases (97%), with one overestimation and two under estimations. 3D PC was concordant in 116 of 128 cases (90%), overestimating in six cases, underestimating in six cases. The sensitivity, specificity and diagnostic accuracy for 2D TOF was, respectively 84%, 94%, and 92%, while for 3D TOF was 94%, 100%, and 98%, and for 3D PC 86%, 98%, and 95%. The comparison of the three different MRA techniques provided no statistically significant difference (Friedman test P < 0.05). CONCLUSION: The high degree of diagnostic accuracy of MRA found in the study of the steno-occlusive disease of the carotid arteries confirms the high degree of reliability of this methodology carried out with the 3D TOF technique, compared to 2D TOF and 3D PC.
Subject(s)
Carotid Stenosis/diagnosis , Magnetic Resonance Angiography/methods , Carotid Arteries/pathology , Humans , Sensitivity and SpecificityABSTRACT
This study was carried out in order to investigate the possible detrimental effects on bone of levothyroxine (l-T4) suppressive therapy in female patients who had undergone surgery for differentiated thyroid cancer (DTC). Twenty female (14 premenopausal and 6 postmenopausal) patients receiving l-T4 suppressive therapy for DTC were studied. The sample was selected in such a way as to avoid factors influencing bone metabolism other than l-T4. All patients were monitored by sensitive thyroid-stimulating hormone, free triiodothyronine and free thyroxine assays throughout the follow-up. Nineteen healthy (12 premenopausal and 7 postmenopausal) matched women served as controls. In all subjects bone turnover was evaluated by the measurement of global skeletal uptake of technetium-99m methylene diphosphonate (GSU); bone mineral density (BMD) was measured by quantitative computed tomography at the lumbar spine (LS) and by dual-energy X-ray absorptiometry both at the LS and at three femoral sites: the femoral neck, Ward's triangle and the greater trochanter. No significant difference was found in either GSU or BMD between patients (treated for an average period of 68 months) and controls in the whole sample or in any subgroup. Furthermore, no correlations were found between either GSU or BMD and the duration of therapy, daily doses of l-T4 or results of thyroid function tests. Our data show that carefully monitored l-T4 therapy does not influence skeletal turnover (directly reflected by GSU) or the bone density of the spine and femur.
Subject(s)
Bone and Bones/drug effects , Neoplasm Recurrence, Local/prevention & control , Radiopharmaceuticals , Technetium Tc 99m Medronate , Thyroid Neoplasms/diagnostic imaging , Thyroxine/adverse effects , Absorptiometry, Photon , Adult , Biomarkers/blood , Bone Density/drug effects , Bone and Bones/diagnostic imaging , Female , Follow-Up Studies , Humans , Middle Aged , Postmenopause , Premenopause , Radionuclide Imaging , Thyroid Function Tests , Thyroid Neoplasms/blood , Thyroid Neoplasms/surgery , Thyroxine/therapeutic useABSTRACT
Bone involvement is a common clinical feature in acromegalic patients, though previous studies gave divergent results possibly because of the different gonadal status of the patients studied. To study the influence of estrogen milieu in these patients, we evaluated 23 acromegalic patients with active disease, subdivided into two groups: menstruating and amenorrheal patients, comparable for duration and activity of disease. Forty-two matched women served as controls. Skeletal involvement was studied by measuring: (a) the main biomarkers of bone turnover: serum alkaline phosphatase total activity (AP), bone GLA protein (BGP), serum carboxy-terminal propeptide of type I collagen (PICP), serum type I cross-linked N-telopeptide (ICTP), and urinary pyridinoline and deoxypyridinoline corrected for creatinine (Pyr/Cr, D-Pyr/Cr) and urinary calcium/creatinine ratio (Ca/Cr); (b) bone mineral density (BMD), as measured by quantitative computed tomography both at lumbar spine and distal radius, and by dual X-ray absorptiometry both at lumbar spine and at three femoral sites (Ward's triangle, femoral neck, and great trochanter). AP, BGP, ICTP, Pyr/Cr, D-Pyr/Cr were significantly higher in patients than in controls, independent of the menstrual pattern. Higher PICP levels were found in the whole group and in menstruating acromegalics when compared with control women; no difference was found in amenorrheal patients, who in turn showed higher urinary Ca/Cr values. When patients were considered all together, BMD at spine, femoral neck, and trochanter was higher than in controls. In contrast, when the gonadal status was taking into account and, menstruating and amenorrheal subjects were considered separately, BMD at spine, but not in other sites, was significantly higher in menstruating patients than in controls. In contrast, no difference of BMD values at any site was observed between amenorrheal patients and controls. The mean BMD Z scores allowed us to detect an unequal involvement of different skeletal sites. Our results show that bone turnover is increased in acromegalic women and suggest that GH anabolic effect on bone is more evident in the presence of estrogens and that different skeletal sites may be affected differently by hormone excess.
Subject(s)
Acromegaly/physiopathology , Amenorrhea/physiopathology , Bone Development/physiology , Growth Hormone/blood , Menstruation/physiology , Acromegaly/blood , Acromegaly/urine , Adult , Aged , Alkaline Phosphatase/blood , Amino Acids/urine , Analysis of Variance , Biomarkers/blood , Biomarkers/urine , Bone Density/physiology , Calcium/urine , Creatinine/urine , Estrogens/blood , Female , Humans , Insulin-Like Growth Factor I/analysis , Middle Aged , Osteocalcin/blood , Peptide Fragments/blood , Procollagen/bloodSubject(s)
Lumbar Vertebrae , Spondylitis/pathology , Aged , Female , Humans , Magnetic Resonance Imaging , Male , Middle AgedABSTRACT
In a multicenter evaluation the precision and stability of single slice peripheral Quantitative Computed Tomography (pQCT) systems were assessed. Compared to central Europe the peripheral QCT device is also widely used in the Italian health care system. Phantoms were measured frequently on each machine in four pQCT scanners over a two-year period using an identical automated software program. Intrasite and intersite phantom mineral densities, expressed in units of mg/cm3, were analyzed and examined. The short and long term precision were estimated from the consistency of these measurements using the root mean square error and expressed as coefficient of variation in percent (% CV). Short term precision was good (mean intrasite coefficient of variation (CV) 0.21 +/- 0.056 standard deviation (SD)). Intersite measurements of a single phantom revealed differences between machines of the same type of not more than 2.9 mg/cm3. At four sites frequent phantom measurements revealed a mean CV of 0.18% (range 0.12-0.28). No significant changes in the regression slopes (drift of the machine versus time) were observed. We conclude that the in vitro precision and stability of the single slice pQCT systems are sufficiently high and unlikely to negatively affect the in vivo precision.
Subject(s)
Bone and Bones/diagnostic imaging , Phantoms, Imaging , Tomography, X-Ray Computed/methods , Absorptiometry, Photon , Bone Density/physiology , Humans , In Vitro Techniques , Linear Models , Reproducibility of ResultsABSTRACT
INTRODUCTION: A new noninvasive technique, dynamic Magnetic Resonance Angiography (MRA) during rapid infusion of paramagnetic contrast medium, has been recently developed for the study of neck vessels. This study was carried out to optimize technical parameters. MATERIALS AND METHODS: Twenty healthy volunteers (10 men and 10 women; age range: 25 to 50 years) were examined with a 1.5 T MR unit equipped with fast imaging software and a dedicated coil. Dynamic MRA was performed using fast spoiled gradient recalled (fast SPGR) sequences acquired on the coronal plane 13 s after contrast medium injection. Imaging parameters were: Echo Time (TE): 1 ms, Repetition Time (TR): 8 ms, flip angle: 60 degrees, matrix 256 x 128, number of excitations: 1, field of view: 18 x 13 cm, number of partitions per slab: 28, slice thickness: 1 mm, acquisition time: 32 s. A dose of .2 mmol/kg of paramagnetic contrast medium was administered with an MR compatible automatic injector, at a speed rate of 1.5 ml/s. Angiographic images were postprocessed with the maximum intensity projection (MIP) and targeted MIP algorithms. RESULTS: Using the above parameters and rapid contrast medium injection, the carotid arteries on the coronal plane (including the vessels from the proximal aspect of the common carotid arteries to the intracranial tract of the internal carotid arteries) in 18 cases. In the other two cases the tortuosity and the position of the carotid arteries on two different planes, prevented their complete visualization. The vertebral arteries were completely demonstrated in 50% of the investigated population. Partial or total overlapping of jugular veins did not affect the recognition of the carotid vessels in 10 cases, also with targeted MIP postprocessing. DISCUSSION: The vascular semiology of dynamic gadolinium enhanced MRA seems to be closer to that of conventional angiography than of conventional MRA, likely due to the same modality of vessel depiction, based on contrast medium administration. Flow artifacts, the major pitfall of conventional MRA causing signal void and overestimation of stenosis grade, are not frequent in dynamic MRA. CONCLUSIONS: Gadolinium enhanced dynamic MRA ensures panoramic and high resolution angiographic-like depiction of the neck vessels, providing rapid and excellent definition of vascular morphology. Thus dynamic MRA appears to be a substantial alternative to conventional MRA and conventional angiography.
Subject(s)
Carotid Arteries/anatomy & histology , Contrast Media/administration & dosage , Gadolinium DTPA/administration & dosage , Magnetic Resonance Angiography/methods , Adult , Female , Humans , Infusions, Intravenous , Magnetic Resonance Angiography/instrumentation , Male , Middle Aged , Reference ValuesABSTRACT
The Authors report their personal experience with postoperative neuroradiologic studies in surgical patients with a herniated disk and/or degenerative cervical spondylosis. Twenty-six patients were enrolled: 16 of them underwent anterior diskectomy, 7 posterior decompressive laminectomy and 3 vertebral body removal. The patients were submitted to pre- and postoperative MRI with high field equipment (Signa 1.5 T, General Electrics), using sagittal SE T1- (TR/TE 360/15), PD and T2-weighted (TR/TE/FA 2000/40/120) sequences and T2-weighted GE axial sequences (TR/TE/FA 400/34/30). FSE sequences (TR/TE/ETL 4000/95/8) were used in 15 cases instead of the above T2-weighted SE sequences. The main postoperative MR findings were analyzed. In particular, the morphological and signal features of bone grafts, of vertebral end-plates, of the subchondral bone and of the surgical site were studied. After anterior diskectomy, the most frequent MR features were massive signal changes in the bone graft and lower vertebral plates, which were hypointense in T1 and hyperintense in T2; the adjacent subchondral bone also exhibited signal changes. Other postoperative MR findings accounted for early postoperative mobility (4 cases of persistent myelomalacia and 3 of bone graft fracture with consequent spinal instability) and late mobility (2 cases of herniated disk, 5 of spinal stenosis and one pseudomeningocele). The main limitation of MRI in postoperative cervical spine studies was the presence of ferromagnetic artifacts during SE, and even more GE, sequences; these artifacts were the main cause of misdiagnoses. In our experience, this troublesome limitation was overcome with FSE sequences but diagnostic accuracy remained poor in 4 patients. MRI, thanks to its multiparametric and multiplanar yield, is the gold standard for the examination of several early and late postoperative features and of postoperative mobility in the cervical spine. Moreover, T2-weighted FSE acquisitions are better than conventional SE to this purpose, because examination time is shorter, myelographic effect is improved and the sensitivity to ferromagnetic artifacts reduced.