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PubMed1999

Brain imaging studies of cocaine abuse: implications for medication development.

Contemporary in vivo brain imaging techniques confer the ability to assess brain function and structure noninvasively, and thereby can yield information to help guide the development of new treatments for substance abuse. The advantages and limitations of the major imaging modalities (positron emission tomography [PET], single photon emission computed tomography [SPECT], structural and functional magnetic resonance imaging [MRI, fMRI, respectively]) are discussed with respect to their applicability to research on cocaine abuse. The effects of acute administration of cocaine have been studied using PET and fMRI, with PET manifesting decreases in cerebral glucose metabolism and blood flow, and fMRI revealing regional effects that are correlated temporally with subjective responses. In addition, studies of drug abusers, abstinent from cocaine for various lengths of time, have revealed persistent differences in brain function and structure, especially in the frontal cortex, when compared with parameters in the brains of subjects who do not use illicit drugs of abuse. PET studies also have revealed abnormalities in markers for dopaminergic and opioid systems during withdrawal from cocaine. Moreover, studies of cue-elicited craving for cocaine demonstrate a connection between the response to drug-related stimuli and neural elements of cognition and emotion. The future directions of in vivo brain imaging to identify functional and structural alterations in the brains of cocaine abusers are discussed in relation to the development of medications to treat cocaine dependence.

Animals↗
PubMed2001

MRI analysis of right ventricular function in normal and spontaneously hypertensive rats.

Right ventricular structure and function were characterized in spontaneously hypertensive rats (SHR) using non-invasive magnetic resonance imaging (MRI) techniques. These studies therefore complement previous reports preoccupied with left ventricular changes associated with this condition. Eight SHR and eight control normotensive Wistar-Kyoto (WKY) rats were each subdivided into equal age-matched groups of 8 and 12 weeks. The right ventricle was imaged through a series of twelve contiguous 1.37-1.75 mm transverse sections at twelve equally spaced time-points that covered both systole and most of diastole thereby completely reconstructing right ventricular anatomy. This gave measurements of right ventricular myocardial mass that were consistent through all twelve time-points in all four experimental groups throughout their cardiac cycles. However, spontaneous hypertension increased this right ventricular myocardial mass, as well as the end-diastolic (EDV) and end-systolic volumes (ESV). Although stroke volume (SV) was conserved, decreases in ejection fraction (EF), a positive shift in the relationship between SV and EDV, and reduced indices of systolic ejection rates in SHR rats compared with the age-matched normal WKY controls indicated significant systolic dysfunction. Additionally, reductions in the rates of diastolic relaxation suggested the onset of diastolic dysfunction. Thus, the non-invasive nature of MRI has made it possible for the first time to demonstrate alterations in structure of the right ventricle and in quantitative indicators of its systolic and diastolic function in the SHR model of hypertension.

Animals↗
PubMed2002

Use of magnetic resonance imaging in short stature: data from National Cooperative Growth Study (NCGS) Substudy 8.

The primary use of magnetic resonance imaging (MRI) in the evaluation of children with short stature (SS) is to discover lesions in the central nervous system (CNS), particularly tumors that may require intervention. MRI has a secondary role in identifying structural abnormalities responsible for growth hormone deficiency (GHD). We examined data from the National Cooperative Growth Study (NCGS) Substudy 8 to determine how American physicians are using MRI in evaluating children with SS. Of the 21,738 short children enrolled in NCGS, 5% underwent MRI during their follow-up. Children who had GH stimulation testing were more likely to have had an MRI than those in whom no GH stimulation test was performed (19% vs 2%, p <0.0001). Moreover, children diagnosed with severe GHD (maximum GH <5 ng/ml) were more likely to have an abnormal finding on MRI. Of these patients, 27% demonstrated an abnormality as compared to 12% and 12.5% in patients with partial GHD and normal GH stimulation test results (>10 ng/ml), respectively. Abnormalities unrelated to the hypothalamus or pituitary represented 30% of these findings, while disorders in pituitary anatomy, including pituitary hypoplasia, pituitary stalk interruption, and ectopic posterior pituitary, represented an additional 30% of abnormal MRI examinations. CNS tumors comprised 23% of abnormal findings in these patients. We conclude that MRI provides significant value in the evaluation of children with SS, by identifying CNS tumors associated with growth failure as well as anatomical abnormalities of the pituitary. These findings are useful in confirming the diagnosis of GHD in children and identifying potential candidates for continued GH replacement in adulthood.

Body Height↗
PubMed2006

Visibility of the polypropylene tape after tension-free vaginal tape (TVT) procedure in women with stress urinary incontinence: comparison of introital ultrasound and magnetic resonance imaging in vitro and in vivo.

OBJECTIVE: To determine whether introital sonography and magnetic resonance imaging (MRI) after TVT (tension-free vaginal tape) insertion can depict the polypropylene tape, and thus be used for patient follow-up. METHODS: The study comprised an experimental part, which investigated in-vitro visualization of the polypropylene tape in a model (phantom), and a clinical part, in which 20 women (mean age, 53.4 years) with clinically and urodynamically proven stress urinary incontinence without prolapse were investigated by introital ultrasound and MRI before and 13 months after the TVT procedure. RESULTS: In the phantom, the polypropylene tape was depicted with a low signal intensity by MRI and as a highly echogenic structure by ultrasound. In the clinical study, introital ultrasound in a mediosagittal orientation depicted the vaginal tape in all patients: it was located under either the midurethra (n = 16) or the lower urethra (n = 4), and in either the muscular coat of the urethra (n = 8) or in the urethrovaginal space (n = 12), the tape was either flat (n = 6) or curled up (n = 14), and there was no retropubic visualization of the tape. Overall, depiction by MRI was limited, and was poorer in comparison with ultrasound, especially when the tape had a sub- or paraurethral location. Retropubically, however, MRI identified the tape near the periosteum of the pubic bone (55% of cases), in the retropubic space (37.5% of cases), or near the bladder wall (7.5% of cases). CONCLUSION: Sonography is recommended for evaluation of the suburethral and paraurethral tape portions, while MRI is suitable for retropubic evaluation after the TVT procedure.

Adult↗
PubMed1994

[Echography and magnetic resonance of the penis. I. Its anatomy].

The use of such new diagnostic imaging methods as ultrasonography (US) and Magnetic Resonance Imaging (MRI) has given radiology an increasingly important role in the study of penis abnormalities. The normal anatomy of the penis was investigated with US with real-time units, high-frequency linear probes, and with an 0.5-T MR unit. The two methods are definitely better than conventional radiologic techniques because they allow the direct and detailed demonstration of all anatomical structures. Both the normal and the abnormal anatomy are better depicted when the exam is performed after pharmacologically induced erection. The normal US and MR features of the different anatomical structures must be known to diagnose penis conditions. US exhibited better spatial resolution than MRI and demonstrated very small structures which may be missed at MRI because of gap interslices. On the other hand, MRI exhibited better contrast resolution, especially on T2-weighted sequences. Thus, the two imaging methods must be considered as complementary, even though US is suggested as the method of choice because of its cost-effectiveness and widespread availability.

Evaluation Studies as Topic↗
PubMed2003

Renal and systemic pH imaging by contrast-enhanced MRI.

Perturbations of renal and systemic pH accompany diseases of the kidney, such as renal tubular acidosis, and the ability to image tissue pH would be helpful to assess the extent and severity of such conditions. A dual-contrast-agent strategy using two gadolinium agents, the pH-insensitive GdDOTP(5-) and the pH-sensitive GdDOTA-4AmP(5-), has been developed to generate pH maps by MRI. The renal pharmacokinetics of the structurally dissimilar pH-insensitive contrast agents GdDTPA(2-) and GdDOTP(5-) were found to be similar. On that basis, and on the basis of similarity of structure and charge, the renal pharmacokinetics of GdDOTP(5-) and GdDOTA-4AmP(5-) were assumed to be identical. Dynamic T(1)-weighted images of mice were acquired for 1 hr each following boluses of GdDOTP(5-) and GdDOTA-4AmP(5-). The time-varying apparent concentration of GdDOTP(5-) and the time-varying enhancement in longitudinal relaxation rate following GdDOTA-4AmP(5-) were calculated for each pixel and used to compute pH images of the kidneys and surrounding tissues. MRI pH maps of control mice show acidic regions corresponding to the renal papilla, calyx, and ureter. Pretreatment of mice with the carbonic anhydrase inhibitor acetazolamide resulted in systemic metabolic acidosis and accompanying urine alkalinization that was readily detected by this dual-contrast-agent approach.

Acetazolamide↗
PubMed2000

Markers of tumor invasion are major predictive factors for the long-term outcome of corticotroph microadenomas treated by transsphenoidal adenomectomy.

OBJECTIVE: To assess the postsurgical outcome of patients with corticotroph microadenomas and to define predictors of the long-term outcome, with special emphasis on markers of tumor extension. DESIGN: Prospective study of 53 corticotroph microadenomas treated by enlarged adenomectomy. Patients followed for at least 2 years were classified into two groups: those in long-term remission and uncured patients (immediate failures and recurrences). Pre-, per- and postoperative parameters were analyzed as predictors of the long-term outcome. METHODS: Baseline hormone assessments were performed preoperatively, 8 days after surgery and every 6-12 months thereafter. Pituitary magnetic resonance imaging (MRI) allowed analysis of possible tumor extension to adjacent structures. Apparent completeness of the surgical removal was determined, and fragments labeled either 'tumor' or 'surrounding pituitary tissue' were submitted to serial sectioning. RESULTS: Immediate control of hypercortisolism was achieved in 43/53 patients (81%). However, later recurrences were observed in five patients (9%). Preoperative MRI showed tumor extension into adjacent structures with good specificity (91%) for prediction of surgical failure. Evidence of local invasion at surgery was also significantly predictive of the long-term outcome. A corticotroph adenoma was found at histological examination in 96% of the patients, and 26% had irregular limits, a feature significantly correlated with a poor outcome. Immediate postoperative plasma cortisol did not allow discrimination between long-term remissions and recurrences. CONCLUSION: Surgical failure was best predicted by signs of tumor 'invasiveness' at MRI, confirmed by peroperative examination and histology.

Adenoma↗
PubMed1992

Age-related shrinkage of the mamillary bodies: in vivo MRI evidence.

Mamillary body (MB) is a diencephalic structure hypothesized to be involved in memory, a cognitive function that declines with age. In this study, age-related differences in the size of MB were examined in vivo using magnetic resonance (MR) imaging. The cross-sectional area of the MB was estimated from MR images of the brain in healthy volunteers and neurologically intact patients (age 18-78). The cross-sectional area of the tectum was used as a control region of interest. We found a significant age-related reduction in the area of the MB, but not of the tectum. No sex differences were observed in the size of either structure.

Adolescent↗
PubMed1996

Magnetic resonance imaging of the internal structure of the mouse fetus.

Magnetic resonance imaging (MRI) has potential as an imaging technique in fetal anatomy. In this article are presented images obtained from mouse fetuses at 16 days of pregnancy by means of the ultraconductive MRI system (JEOL AIM270). When fetuses removed from the uterus were fixed with 10% neutral formalin, various organs including heart, liver, lungs and bones were clearly seen, and a clear outline was obtained of the fetal skin and subcutaneous tissue by varying the setting. The same specimens were able to be used for histological evaluation. This MRI system will allow wider application in fetal anatomy and provide additional information about the developing mouse fetus.

Abdomen↗
PubMed1995

[The facial nerve in the petrous bone in thin-layer paratransverse and sagittal magnetic-resonance-tomographic T1-spin-echo and FLASH images].

PURPOSE: It is difficult to effect visualization and delineation of the facial nerve and its neighbouring structures in the temporal bone with conventional MRI examination protocols. We tested temporal bone MRI with 2 mm slices and compared T1-weighted FLASH (TR = 400 ms, TE = 10 ms, 90 degrees flip angle) and spin-echo (TR = 540 ms, TE = 15 ms) sequences. PATIENT AND METHODS: 5 volunteers and 14 patients were examined with the head coil of a 1.0T whole body MRI scanner (Impact, Siemens, Erlangen) with para-transversal images orientated parallel to the inferior outline of the clivus and sagittal images orientated along the brainstem. RESULTS: The facial nerve and its neighbouring structures could be reliably visualized and differentiated along its entire course. The FLASH sequence was superior to the spin-echo sequence. 8 of 11 patients with peripheral facial nerve palsy showed contrast enhancement. In two patients, local swelling of the affected facial nerve was evident. CONCLUSION: The MRI technique tested here seems promising for temporal bone examinations.

Adult↗
PubMedDate not supplied

Magnetic resonance imaging of the brain of normal neonatal foals.

Magnetic resonance imaging (MRI) was performed on the brain of 5 normal, anesthetized, neonatal (age 3-to-6 days) Quarter Horse foals. The objectives of the study were to develop a technique for imaging the brain of neonatal foals, and to ascertain their normal brain anatomy. Intravenous propofol was administered for induction and maintenance of general anesthesia. Using spin echo MR techniques, T1 weighted sagittal and transverse views, and spin density and T2 weighted transverse views were successfully made of each foal. MR images provided excellent visualization of many anatomic structures of the brain and head. MRI of the brain is feasible for selected neonatal equine patients.

Anesthesia, Intravenous↗
PubMed1998

Behçet's disease and the nervous system.

Behçet's disease is a multisystem inflammatory disorder with unknown aetiology. It is a disease of young adults with a more severe course in males subjects. Its prevalence is high in the Mediterranean basin and Japan and has been linked with human leucocyte antigen B5 (HLA-B5) in those countries. According to the diagnostic criteria formed by the International Study Group, recurrent oral ulceration is a prerequisite, with two more typical symptoms or signs. Neurological involvement is one of the most devastating manifestations of Behçet's disease. The involvement is either caused by primary neural parenchymal lesions (neuro-Behçet) or secondary to major vascular involvement (vasculo Behçet). The course is relapsing-remitting, secondary progressive or primary progressive. The most commonly involved area is the brain stem, with additional symptoms or signs, hemispherical involvement with mental changes being the most common. Intracranial hypertension, usually owing to dural sinus thrombosis, has a special place in Behçet's disease. The most common clinical findings are pyramidal signs. Sensory symptoms or signs are much less frequent, and hemianopia and higher cortical function disturbances as well as pure cerebellar syndrome are rare features. Cerebrospinal fluid usually has a high protein content and/or pleocytosis. Notably, in the acute period most patients have lesions shown by magnetic resonance imaging (MRI) extending from the brain-stem to diencephalic structures. Differential diagnosis from multiple sclerosis can be difficult in patients with hemispheric white matter MRI hyperintensities. Immunosuppressives are used in treatment.

Adult↗
PubMed1994

Magnetic resonance imaging of the pharynx and larynx.

Imaging of the pharynx and larynx has been a difficult challenge for many years. The advent of magnetic resonance imaging (MRI) with its superior soft tissue contrast resolution and multiplanar capabilities has allowed the imaging specialist to examine these structures with unparalleled precision. The recent developments in MRI can also aid the oncologist, surgeon, and radiation therapist in developing a more comprehensive treatment plan for patients with pharyngeal and laryngeal neoplasms. This article describes the important advances in MRI of the pharynx and larynx.

Humans↗
PubMed2002

Temporopolar changes in temporal lobe epilepsy: a quantitative MRI-based study.

OBJECTIVES: To quantify the morphologic changes of temporopolar structures to better understand the pathophysiology of anterior temporal white matter increased T2 signal observed in temporal lobe epilepsy (TLE). METHODS: MRI was performed in 30 patients with TLE and in 30 normal control subjects and independently assessed by visual analysis and quantitative measurements. Specifically, the temporal pole (TP) volume, as well as its gray and white matter components, was measured using three-dimensional T1 MR images and a semiautomatic protocol. The authors tested whether the presence of an increased T2-weighted signal in the anterior temporal white matter was associated with significant TP atrophy. The associations between the TP volume and MRI signs of hippocampal sclerosis, age at onset, seizure frequency, duration of illness, and a history of febrile convulsions were also studied. RESULTS: Both right and left TLE populations demonstrated a reduction of the temporopolar white and gray matter volumes ipsilateral to seizure onset (p < 0.02 in right TLE; p < 0.0001 in left TLE). Twenty-two patients (72%) exhibited significantly abnormal TP volume measurements, which correctly lateralized the epileptogenic zone in all cases. The presence of an increased T2-weighted signal in the anterior temporal white matter (ISWM), but not that of hippocampal sclerosis, was associated with a greater TP volume asymmetry index (p < 0.05). CONCLUSIONS: The temporal pole is frequently atrophic ipsilateral to seizure onset in refractory TLE. The association between TP atrophy and ISWM suggests that both abnormalities might derive from a common pathologic process.

Adolescent↗
PubMed1987

[Magnetic resonance imaging of the knee. Preliminary study of non-neoplastic osteoarticular pathology].

Magnetic Resonance Imaging (MRI) has been applied to musculoskeletal pathoanatomy and has proved to be useful in the detection and characterization of knee pathology. Thirty-two acutely injured knees and 8 normal knees were examined. The images were obtained in the Diagnostic Centre RMRC of Naples on a 0.5 T superconductive magnet system, using a surface coil and a spin-echo pulse sequence (SE 600/28 ms). The examined limb was immobilized and bent at 8-10 degrees, extrarotated for the examination of the anterior cruciate ligament (ACL) only. Images were obtained on a 256 x 256 matrix and had a 2 or 4-mm thickness. MRI clearly showed all the anatomical structures. The anterior and posterior cruciate ligaments (ACL and PCL) and the patellar ligament were shown by sagittal SE images through the intercondylar notch; the tibial and fibular collateral ligaments (TCL and FCL) were evaluated on coronal SE images; the articular capsula and menisci on axial transverse SE images. Objective criteria for ACL and PCL tears were: lack of continuity of the signal and change in signal intensity; in meniscal pathology, menisci with small linear regions of increased signal or with grossly truncated shape were interpreted as tears. Preliminary results of this study indicate that MRI together with clinical evaluation may be an useful non-invasive procedure in the assessment of acute injuries of the knee.

Diagnosis, Differential↗
PubMed2001

Normal fetal anatomy as visualized with fast magnetic resonance imaging.

The development of ultrafast sequences has revolutionized fetal magnetic imaging (MRI). Fetal anatomy can be characterize precisely by MRI. This is particularly true for evaluation of the central nervous system, for which magnetic resonance (MR) evaluation is superior to ultrasound evaluation. MR allows analysis of development of the cerebrum as well as posterior fossa structures. Awareness of the normal sequence of maturation as well as the approximate timing of development of key structures is useful for evaluating the developing fetus. MRI also permits evaluation of the oropharynx, lungs, diaphragm, and intra-abdominal and retroperitoneal structures. Occasionally, beautiful depiction of smaller structures, including extremities and details of the face and neck may be obtained, but this is dependent on the orientation of the fetus and the plane of imaging as well as the section thickness. MRI is useful in assignment of fetal gender as well as in evaluation of the chorionicity of twin gestations. This report illustrates the normal appearance of the developing fetus as seen on fast sequences during the second and third trimesters.

Embryonic and Fetal Development↗
PubMedDate not supplied

Noninvasive staging of lung cancer.

Accurate evaluation of disease extent is mandatory when the diagnosis of resectable lung cancer is established. Staging has a significant impact on subsequent therapeutic options and prognosis. Radiologists can now rely on numerous instruments, each with different advantages and limitations. The procedure of choice is still chest X-ray whose intrinsic limitations require better tumor characterization with chest CT. CT difficulties in the differential diagnosis between the tumor and secondary changes occurring in adjacent structures can be overcome by 18F-FDG-PET or MRI. Functional information is acquired with the former and multiparametric information with the latter. According to the case, further extension to adjacent structures can be evaluated based on CT or MRI. For lymph node and distant metastasis PET is increasingly used, except for brain parenchyma where MRI is definitely more accurate in the detection of brain metastasis.

Humans↗
PubMed2002

Validation of diffusion tensor MRI-based muscle fiber tracking.

Diffusion-tensor (DT) MRI fiber tracking may potentially be used for in vivo structural analysis. The purpose of this study was to assess quantitatively the ability of a DT-MRI fiber-tracking algorithm to measure the fiber orientation (pennation) in skeletal muscle in vivo. In five adult Sprague-Dawley rats, the pennation angle (theta) was measured in the rat lateral gastrocnemius with DT-MRI (theta(DT-MRI)) and by direct anatomical inspection (DAI) (theta(DAI)). The mean theta(DT-MRI) was not significantly different from the mean theta(DAI). In addition, the two methods were highly correlated (r = 0.89) and the regression of theta(DT-MRI) on theta(DAI) resulted in a slope not significantly different from 1 and an intercept not significantly different from zero. These data indicate that DT-MRI-based fiber tracking as implemented here is a valid tool for in vivo structural analysis of small-animal skeletal muscle.

Animals↗