MR imaging of Kallmann syndrome, a genetic disorder of neuronal migration affecting the olfactory and genital systems

PURPOSE: We report the MR findings in nine patients with clinical and laboratory evidence of Kallmann syndrome (KS), a genetic disorder of olfactory and gonadal development. In patients with KS, cells that normally express luteinizing hormone-releasing hormone fail to migrate from the medial olfactory placode along the terminalis nerves into the forebrain. In addition, failed neuronal migration from the lateral olfactory placode along the olfactory fila to the forebrain results in aplasia or hypoplasia of the olfactory bulbs and tracts. Patients with KS, therefore, suffer both reproductive and olfactory dysfunction. METHODS: Nine patients with KS underwent direct coronal MR of their olfactory regions in order to assess the olfactory sulci, bulbs, and tracts. A 10th patient had MR findings of KS, although the diagnosis is not yet confirmed by laboratory tests. RESULTS: Abnormalities of the olfactory system were identified in all patients. In particular, the anterior portions of the olfactory sulci were uniformly hypoplastic. The olfactory bulbs and tracts appeared hypoplastic or aplastic in all patients in whom the bulb/tract region was satisfactorily imaged. In two (possibly three) patients, prominent soft tissue in the region of the bulbs suggests radiographic evidence of neurons that have been arrested before migration. CONCLUSIONS: Previous investigators of patients with KS used axial MR images to demonstrate hypoplasia of the olfactory sulci but offered no assessment of the olfactory bulbs. In the present study we used coronal images to show hypoplasia of both olfactory sulci and bulbs. In addition, we found what we believe to be the radiologic correlate of arrested neuronal migration in KS.     

Magnetic resonance imaging of the olfactory apparatus

The magnetic resonance imaging visualization of the olfactory apparatus is reported in this article. We used a superconductor-type magnetic resonance device (Siemens Magnetom H15 (1.5 T) with a surface coil. The subjects were patients with posttraumatic anosmia. The olfactory bulbs were clearly visualized in the frontal plane magnetic resonance images, the olfactory bulbs and the foramina of the cribriform plate were visualized in the sagittal section, and the olfactory bulbs, tracts, and other structures were visualized in the coronal sections. The olfactory nerves could not be seen.     

CD46 (membrane cofactor protein of complement, measles virus receptor): structural and functional divergence among species (review)

OBJECT: In this retrospective study, the authors analyzed the frequency, anatomical distribution, and appearance of traumatic brain lesions in 42 patients in a posttraumatic persistent vegetative state. METHODS: Cerebral magnetic resonance (MR) imaging was used to detect the number of lesions, which ranged from as few as five to as many as 19, with a mean of 11 lesions. In all 42 cases there was evidence on MR imaging of diffuse axonal injury, and injury to the corpus callosum was detected in all patients. The second most common area of diffuse axonal injury involved the dorsolateral aspect of the rostral brainstem (74% of patients). In addition, 65% of these patients exhibited white matter injury in the corona radiata and the frontal and temporal lobes. Lesions to the basal ganglia or thalamus were seen in 52% and 40% of patients, respectively. Magnetic resonance imaging showed some evidence of cortical contusion in 48% of patients in this study; the frontal and temporal lobes were most frequently involved. Injury to the parahippocampal gyrus was detected in 45% of patients; in this subgroup there was an 80% incidence of contralateral peduncular lesions in the midbrain. The most common pattern of injury (74% in this series) was the combination of focal lesions of the corpus callosum and the dorsolateral brainstem. In patients with no evidence of diffuse axonal injury in the upper brainstem (26% in this series), callosal lesions were most often associated with basal ganglia lesions. Lesions of the corona radiata and lobar white matter were equally distributed in patients with or without dorsolateral brainstem injury. Moreover, cortical contusions and thalamic, parahippocampal, and cerebral peduncular lesions were also similarly distributed in both groups. CONCLUSIONS: The data indicate that diffuse axonal injury may be the major form of primary brain damage in the posttraumatic persistent vegetative state. In addition, the authors demonstrated in this study that MR imaging, in conjunction with a precise clinical correlation, may provide useful supportive information for the accurate diagnosis of a persistent vegetative state after traumatic brain injury.     

Influence of smell loss on taste function.

The influence of damage to one sensory system on the functioning of other sensory systems has been of scientific interest for over a century. Recently it has been suggested that damage to the olfactory system (CN I) decreases the ability to taste; that is, to perceive sweet, sour, bitter and salty sensations via CN VII, IX, and X. If true, this would be in contrast to most other sensory systems, where compromise typically leads to either cross-modal enhancement of function or to no effects at all. In the present study, data from both regional and whole-mouth taste tests of 581 patients presenting to a smell and taste center with varying degrees of olfactory function were evaluated to address whether olfactory loss is associated with taste loss. No significant influence of olfactory dysfunction on any measure of taste perception was found when the effects of sex, age, and etiology were controlled. These data suggest that smell loss, per se, has no meaningful influence on taste function, and that clinical associations between smell and taste dysfunction, when observed, likely reflect comorbid influences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory-evoked regional cerebral blood flow in Alzheimer's disease.

Olfaction is impaired in Alzheimer's disease (AD). It was hypothesized that AD would reduce olfactory-evoked perfusion in mesial temporal olfactory (piriform) cortex, where neuropathology begins. Seven AD patients and 8 elderly controls (ECs) underwent olfactory threshold and identification tests and olfactory stimulation during positron emission tomography. Odor identification was impaired in AD, but threshold was not. Olfactory stimulation in ECs activated right and left piriform areas and right anterior ventral temporal cortex. AD patients had less activation in right piriform and anterior ventral temporal cortex but not in the left piriform area. Although orbital cortex did not activate in ECs, there was a significant between-groups difference in this area. Right piriform activation correlated with odor identification. Impaired odor identification likely reflects sensory cortex dysfunction rather than cognitive impairment. Given olfactory bulb projections to the mesial temporal lobe, olfactory stimulation during functional imaging might detect early dysfunction in this region. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hypothalamic hamartomas and gelastic epilepsy: a spectroscopic study

BACKGROUND: Patients with hypothalamic hamartomas present with epileptic attacks of laughter and later experience multiple seizure types and cognitive decline, suggestive of secondary generalized epilepsy. It has been suggested in the past that gelastic seizures originate in the temporal lobes rather than in the hamartoma, but temporal resections have been ineffective. Recent electrophysiologic evidence suggests that the epileptogenic discharges may originate in the hamartoma itself. METHODS: We used proton magnetic resonance spectroscopic imaging to quantify the amount of neuronal damage in the temporal lobes and hamartomas of patients with hypothalamic hamartomas and gelastic seizures. Five patients were studied and the relative intensity of N-acetylaspartate to creatine (NAA/Cr) was determined for both temporal lobes as well as for the hamartoma. These values were compared with signals from the temporal lobes and hypothalami of normal control subjects. RESULTS: NAA/Cr was not significantly different from normal control subjects for either temporal lobe, nor was there a significant asymmetry between the two temporal lobes for any of the patients. NAA resonance signals were present in the hamartomas, and the ratio of NAA to Cr was decreased in the hamartomas compared with the hypothalami of normal control subjects (t = 4.5, p = 0.005). CONCLUSIONS: We found no detectable neuronal damage in the temporal lobes of patients with hypothalamic hamartomas and gelastic epilepsy. This is further evidence that gelastic seizures do not originate in the temporal lobes of these patients.     

Enzyme determination in vitro of inhibitor activity of beta-lactamase from tazobactam. Comparison with high performance liquid chromatography

Most physiological studies of the human olfactory system have concentrated on the cortical level; the olfactory bulbar level has been studied rarely. We attempted to stimulate the human olfactory mucosa by electrical pulse to detect the bulbar potentials. Electrical stimulation (2 mA, 0.5 ms) of the human olfactory mucosa evoked a change in potential recorded from the frontal sector of the head. A negative peak of the evoked potential that occurred at 19.4 ms (grand means, n = 5) after stimulation was the clearest. The highest amplitude of the potential was recorded from the frontal sector of the head on the stimulated side. Our findings were similar to the experimental results obtained from the olfactory bulbs of animals. This evoked potential was considered to be the human olfactory bulbar potential. When the subjects were stimulated by applying electricity to the olfactory mucosa, no sensation of smell occurred even though evoked potentials were recorded. Evoked potentials were recorded only when the stimulating electrode was located in the olfactory cleft. When the stimulating electrode was outside the olfactory cleft, the stimulation caused pain. The trigeminal nerve seemed to be stimulated by electricity. Olfactory evoked potentials produced by the electrical stimulation of the human olfactory mucosa should aid the research on human olfactory physiology, and may be applicable to clinical tests of olfactory dysfunction.     

Bilateral temporal lobe volume reduction parallels cognitive impairment in progressive aphasia

BACKGROUND: Patients with isolated aphasia in the absence of other cognitive abnormalities have been the focus of several studies during the past decade. It has been called primary progressive aphasia (PPA), and the typical features of this syndrome are marked atrophy of the left temporal lobe according to the radiological examination and a language disorder as the initial symptom. In previous studies of PPA, the selection of the patients was based mainly on linguistic symptoms. Now, when computed tomography or magnetic resonance imaging scans are part of the routine investigation of cognitive impairment and suspected dementia, the patients with lobar atrophy will be found at an earlier stage. In the present study, we used a new approach and defined the study group by selecting patients with obvious left temporal lobe atrophy, assessed by MRI, and we referred to them as patients with temporal lobe atrophy (TLA). OBJECTIVE: To identify the features that distinguish TLA from other primary neurodegenerative disorders. PATIENTS: Six patients with TLA were compared with patients with Alzheimer disease (AD), patients with frontal lobe dementia (FLD), and healthy control subjects. METHODS: The investigations included magnetic resonance imaging volumetry, single photon emission computed tomography, and neuropsychologic and linguistic evaluations. RESULTS: In the TLA group, the mean volume of the left temporal lobe was 35% smaller than the right, while in the AD and FLD groups, the atrophy was symmetrical and bilateral. In the TLA group, the absolute volumes of the temporal lobes were significantly smaller on the left side compared with the AD and FLD groups, whereas there was no difference on the right side. The cerebral blood flow pattern in TLA was asymmetric and differed from that in the other study groups. All patients with TLA had a history of progressive Wernicke-type aphasia, ranging from 2 to 6 years. They showed primary verbal memory impairment but had preserved visuospatial functions. The clinical condition of all patients with TLA deteriorated during the study period; severe aphasia developed, and the patients exhibited signs of frontal lobe dysfunction. Serial volumetric measurements in 4 of 6 patients showed an annual 8% to 9% decrease of both left and right temporal lobes. CONCLUSIONS: The initial marked asymmetry in cognitive function found in patients with TLA contrasts with the general decline found in patients with AD. The bilateral degenerative process evident in patients with TLA paralleled the clinical deterioration, indicating TLA to be a non-AD lobar atrophy that develops into generalized cognitive dysfunction and dementia.     

Sudden hearing loss: frequency of abnormal findings on contrast-enhanced MR studies

BACKGROUND AND PURPOSE: Our purpose was to determine the frequency of abnormal findings on contrast-enhanced high-resolution MR imaging studies in patients with sudden hearing loss. METHODS: Seventy-eight consecutive patients with sudden hearing loss underwent contrast-enhanced MR imaging of the temporal bone, cerebellopontine angle, and brain. Additional tests included audiologic examination, electrocochleography, fistula tests, and serologic tests for viral agents and autoimmune disorders. RESULTS: Probable causes of the sudden hearing loss in these patients included viral or immune-mediated disease, Meniere disease, vascular disorder, syphilis, neoplasm, multiple sclerosis, and perilymphatic fistula. Twenty-four (31%) of the 78 patients were found to have abnormal imaging results early in the course of their work up and treatment. CONCLUSION: The prevalence of abnormal findings on contrast-enhanced MR studies is higher than previously reported in patients with sudden hearing loss.     

Olfactory prodromal symptoms and unilateral olfactory dysfunction are associated in patients with right mesial temporal lobe epilepsy

PURPOSE: We report a patient with mesial temporal lobe epilepsy (MTLE) with olfactory prodromal symptoms manifested as an unpleasant smell of onions, who was found to have an ipsilateral deficit of olfactory naming (olfactory agnosia). METHODS AND RESULTS: Preoperative olfactory testing revealed a selective right-sided olfactory deficit for naming of odors. Olfactory threshold was within the normal range. The patient has been seizure free after selective amygdalohippocampectomy for 4 months. No olfactory prodromal events have occurred since surgery. Olfactory testing 3 months after resection showed that right-sided odor naming was still impaired. CONCLUSIONS: We conclude that olfactory prodromal symptoms may be associated with unilateral olfactory dysfunction, and lateralization of seizure origin may be possible by unilateral olfactory testing.     

Olfactory function in young adolescents with Down's syndrome

Decreased ability to smell is present in adults with Down's syndrome, many of whom are known to have brain pathology analogous to that seen in Alzheimer's disease. Because olfactory loss is well documented in Alzheimer's disease, the question arises whether young adolescents with Down's syndrome, who have no clear Alzheimer's disease-like neuropathology, also exhibit olfactory dysfunction. To consider this issue, standardised tests of odour discrimination and identification were administered to 20 young adolescents with Down's syndrome (mean age (SD) 13.89 (1.98) years) and their test scores were compared with 20 mentally retarded and 20 non-mentally retarded control subjects matched to the patients with Down's syndrome on the basis of cognitive ability. No significant differences in olfactory function were found among the three study groups. These findings, along with those from studies of olfactory function in older patients with Down's syndrome, suggest that Down's syndrome related olfactory dysfunction occurs only at ages when Alzheimer's disease-like pathology is present.     

Gliomatosis cerebri

PURPOSE: To characterize gliomatosis cerebri on computed tomographic (CT) and magnetic resonance (MR) images. MATERIALS AND METHODS: MR and CT studies of 22 patients with cerebral gliomatosis were reviewed retrospectively. Tumor was confirmed with autopsy (n=5) or biopsy. Distribution and extent of disease were assessed, and disease progression was followed. RESULTS: Tumor involved at least two lobes of the brain in all patients, with extension to the corpus callosum in 12, basal ganglia and thalamus in 17, brain stem in three, and cerebellum in two patients. Widespread invasion with hyperintensity was noted on proton-density- and T2-weighted MR images. At CT, areas of hypo- or isoattenuation were noted, and no contrast enhancement occurred. Extent of tumor was greater on MR images than on concurrent CT scans in all patients. The MR findings closely correlated with the autopsy findings. CONCLUSION: Gliomatosis cerebri is best detected with MR imaging. The pattern is infiltrative with enlargement of cerebral structures.     

Evaluation of tibial plateau fractures: efficacy of MR imaging compared with CT

OBJECTIVE: CT is often used after plain films to evaluate fractures of the tibial plateau. Because MR imaging can show associated soft-tissue injuries as well as fractures, we hypothesize that MR is superior to CT for imaging these injuries. Accordingly, we compared the efficacy of MR imaging and CT in 22 patients with tibial plateau fractures. SUBJECTS AND METHODS: CT with two-dimensional reconstruction and MR examinations were performed in 22 patients with tibial plateau fractures. The images were interpreted by four radiologists and two orthopedic surgeons. Findings on CT scans and plain films were used to determine the configuration of the fractures and to classify them according to the Schatzker system. This was done with findings on MR images and plain films at a separate session. The MR images were also evaluated for ligamentous and meniscal injuries. A qualitative side-by-side comparison of two-dimensional CT scans and MR images for depiction of fracture configuration was done. Imaging results were correlated with observations from physical examinations in all patients and with surgical findings in 12 patients. RESULTS: All of the six types of fractures of the Schatzker classification were observed in this series. Comparison of two-dimensional CT reconstructions and MR images for depiction of fracture configuration revealed that the two techniques were equal in 14 patients, MR imaging was superior to CT in five patients, and CT was superior to MR imaging in three patients (who had very complex and comminuted fractures). In addition, MR imaging showed 12 complete ligamentous tears and 15 partial ligamentous tears in 15 (68%) of the 22 patients. MR showed meniscal injuries in 12 (55%) of the 22 patients. CONCLUSION: MR imaging was equivalent or superior to two-dimensional CT reconstruction for depiction of fracture configuration in most patients. In addition, MR showed significant soft-tissue injuries. We believe that MR imaging is the preferable imaging technique for most patients with fractures of the tibial plateau.     

Fast fluid-attenuated inversion recovery (FLAIR) compared with T2-weighted spin-echo in the magnetic resonance diagnosis of mesial temporal sclerosis

RATIONALE AND OBJECTIVES: The authors compare coronal fast fluid-attenuated inversion recovery (FLAIR) with coronal T2-weighted spin-echo (SE) magnetic resonance (MR) techniques in the diagnosis of mesial temporal sclerosis (MTS). METHODS: In this prospective study, the authors assessed MR scans of 30 patients with drug-resistant temporal lobe epilepsy (based on clinical symptomatology and electroencephalographic registrations) with MR features suggestive of MTS. MR scans of age-, sex-, and scanner-matched patients, referred for MR assessment of white matter disease, without a history of epilepsy and with no visible abnormalities on MR, were used as controls. In 16 patients the MR diagnosis was confirmed by histologic abnormalities consistent with MTS. Coronal T2 SE and FLAIR images of patients and controls were presented to two experienced radiologists in random order for independent blinded review. Hippocampal and associated extrahippocampal temporal lobe abnormalities were used for the diagnosis of MTS. RESULTS: The sensitivity of observer A was 97% for the T2 SE sequence and 100% for the FLAIR; the specificity of observer A for both techniques was 100%. The sensitivity of observer B was 53% for T2 SE and 83% for FLAIR; the specificity for observer B was 93% for the T2 SE and 100% for FLAIR. CONCLUSION: Coronal FLAIR images provide a similar or increased yield in the detection of MTS compared with T2-weighted SE images.     

Polydactyly in a carrier of the gene for the Meckel syndrome

Localized scleroderma is distinct from the diffuse form of scleroderma and does not show Raynaud's phenomenon and visceral involvement. The imaging features in 23 patients ranging from 2 to 17 years of age (mean 11.1 years) were reviewed. Leg length discrepancy and muscle atrophy were the most common findings (five patients), with two patients also showing modelling deformity of the fibula. One patient with lower extremity involvement showed abnormal bone marrow signals on MR. Disabling joint contracture requiring orthopedic intervention was noted in one patient. In two patients with "en coup de sabre" facial deformity, CT and MR scans revealed intracranial calcifications and white matter abnormality in the ipsilateral frontal lobes, with one also showing migrational abnormality. In a third patient, CT revealed white matter abnormality in the ipsilateral parietal lobe. In one patient with progressive facial hemiatrophy, CT and MR scans showed the underlying hypoplastic left maxillary antrum and cheek. Imaging studies of areas of clinical concern revealed positive findings in half our patients.     

Magnetic resonance imaging of focal liver lesions. Comparison of the superparamagnetic iron oxide resovist versus gadolinium-DTPA in the same patient

RATIONALE AND OBJECTIVES: The authors assess the efficacy of static and dynamic magnetic resonance (MR) imaging using the superparamagnetic iron oxide SHU-555A (Resovist) versus standard dose of gadolinium (Gd)-DTPA in patients with focal liver lesions. METHODS: Magnetic resonance imaging was performed in 30 patients suffering from histopathologically verified malignant (n = 22) and benign (n = 8) liver lesions. T2-weighted conventional and fat-suppressed as well as T1-weighted sequences were used before, during, and after fast intravenous administration of Resovist (1 mL/minute) at three doses of 4, 8, and 16 mumol/kg body weight. One week before the Resovist-enhanced MR imaging study 20 patients underwent Gd-DTPA-enhanced MR imaging. RESULTS: Detection rate was improved for metastatic lesions revealing 36 lesions unenhanced versus 53 focal lesions using Resovist-enhanced MR imaging. Gadolinium-DTPA-enhanced scans showed no additional lesion versus unenhanced and Resovist-enhanced MR imaging. Static and dynamic imaging demonstrated no measurable percentage signal intensity loss (PSIL) using Resovist-enhanced MR imaging versus a percentage enhancement of 79.7% in Gd-DTPA enhanced scans. In the dynamic T2-weighted sequences, hepatocellular carcinoma nodules (n = 4) showed a rapid decrease in signal intensity starting at 44 seconds. Postinfusion of Resovist followed by a low, constant increase in signal intensity. Gadolinium-DTPA enhanced scans showed a percentage enhancement of 73.4 focal nodular hyperplasia (FNH) and hemangioma revealed a strong and early dose-dependent PSIL 44 to 60 seconds postinfusion with a prolonged signal loss for the FNH in the late study. Statistical evaluation revealed a statistically significant superiority of Resovist-enhanced MR imaging concerning the detection and delineation of focal liver lesions compared with unenhanced and Gd-DTPA enhanced scans (P < 0.05). CONCLUSIONS: The fast infusion of the new superparamagnetic contrast agent Resovist shows advantages for dynamic and static MR imaging of focal liver lesions.     

The effect of human leukocyte antigen disparity on cyclosporine neurotoxicity after allogeneic bone marrow transplantation

PURPOSE: We examined the relationship between human leukocyte antigen (HLA) matching and the development of cyclosporine (CyA) neurotoxicity in patients undergoing allogeneic bone marrow transplantation, and determined the frequency and imaging characteristics of CyA neurotoxicity in these patients. METHODS: Records of 87 patients who underwent allogeneic bone marrow transplantation were reviewed. Eight patients who presented with visual disturbance and/or seizures and had MR imaging within 24 hours were identified. Transplant donor relatedness was examined, and patients' imaging studies were reviewed. Clinical parameters, including blood pressure, CyA, creatinine, and magnesium levels, and the presence of graft-versus-host disease were reviewed. RESULTS: CyA neurotoxicity was seen more frequently in HLA-mismatched and unrelated donor transplants. The frequency of CyA neurotoxicity was 4% for patients with a 5/6 or 6/6 HLA match, 13% for matched unrelated donor transplants, and 50% for haplotypic 3/6 or 4/6 transplants. Patients with matched unrelated donor transplants and haplotypic transplants presented earlier in the posttransplant time course and had decreased survival time relative to patients with HLA-matched transplants. Imaging abnormalities most commonly affected the occipital lobes and the posterior cerebral hemispheres; both cortical and white matter involvement was identifiable as T1 hypointense and T2 hyperintense signal with associated gyral swelling and sulcal effacement on the initial MR studies. Hypodensity in the affected areas was noted on CT scans. Contrast enhancement was seen in HLA-mismatched and unrelated transplants only. Follow-up imaging showed interval decreases in subcortical edema; however, residual signal abnormality, primarily affecting the cortex, was present in all cases and seen best on proton density-weighted MR images. CONCLUSION: The frequency of severe CyA neurotoxicity increases with increasing HLA disparity, suggesting that immune factors may play a role. CyA neurotoxicity appears to represent a spectrum of disease processes. Disruption of the blood-brain barrier as well as hypoxic or vasculitic cortical injury resulting in MR-detectable cortical signal abnormalities may occur in severe cases.     

The accuracy of CT and MR evaluation of the sella turcica for detection of adrenocorticotropic hormone-secreting adenomas in Cushing disease

PURPOSE: To document the accuracy of CT and MR of the sella turcica for detecting adrenocorticotropic hormone-secreting adenomas in Cushing disease. METHODS: The radiologic findings of the sella turcica prior to transsphenoidal surgery are reviewed in 141 patients who had biochemical evidence of pituitary-dependent Cushing disease. Axial thin-collimation CT scans with sagittal and coronal reformations before and after contrast enhancement were obtained in 125 patients. Seventy-eight patients had MR examinations with a 1.5-T superconducting magnet. In 11 of the patients gadolinium-enhanced MR scans were also obtained. The preoperative interpretation of the imaging studies was correlated with the surgical findings and patients follow-up. RESULTS: The sella turcica was enlarged in 43 cases (30%). In 125 patients reformatted or direct coronal thin-collimation CT scans were available. Seventy-eight of the patients had MR. In the 12 patients with pituitary macroadenomas, the accuracy of CT (n = 10) and MR (n = 10) in respect to detection of the lesion was 100%. Of the 98 microadenomas assessed by CT, 47 (48%) were directly depicted as distinct hypodense lesions. In only 31 of 73 cases (42%), however, could CT predict the precise anatomic location and extent of the lesions. Only patients in whom the hypercortisolism was corrected by later surgery were considered for the correlation analysis. Of the 52 microadenomas assessed by MR, 28 (53%) were directly depicted as distinct lesions of reduced signal intensity on T1-weighted images, and in only 21 of 41 cases (52%) did MR show good correlation to the surgical findings. Some degree of partially empty sella was found in 22% of the patients. CONCLUSIONS: Although both the sensitivity and the diagnostic accuracy of imaging methods of the sella turcica have been considerably improved in comparison with previous reports, they still provide only a minor contribution to the diagnosis and differential diagnosis of Cushing syndrome.     

Localization of abnormal parathyroid glands of the mediastinum with MR imaging

PURPOSE: To determine the sensitivity of magnetic resonance (MR) imaging for preoperative localization of abnormal parathyroid glands in the mediastinum and to compare the sensitivity of MR imaging with those of scintigraphy and ultrasonography (US). MATERIALS AND METHODS: The prospective sensitivity of MR imaging was compared with those of thallium-technetium scintigraphy and US in 25 patients in whom the abnormal gland was located in the mediastinum at surgery. RESULTS: MR imaging had a much higher sensitivity (22 of 25 cases [88%]) than did scintigraphy (11 of 19 cases [58%]) or US (three of 24 cases [12%]). The most common locations for the mediastinal gland were intrathymic (eight of 25 cases) and paraesophageal (six of 25 cases) sites. CONCLUSION: MR imaging should be considered the modality of choice for preoperative localization in this group of patients.     

Efficacy of gadolinium in MR brain imaging of HIV-infected patients

PURPOSE: To determine the value of gadolinium in routine head MR imaging of HIV-infected patients. METHODS: One hundred and three consecutive human immunodeficiency virus-infected patients referred for head MR imaging were scanned without and with intravenous gadopentetate dimeglumine (Gd-DTPA) contrast. RESULTS: The precontrast scans of 82 patients were either normal, or had atrophy or diffuse white matter changes only. Sixteen of these 82 demonstrated enhancing abnormalities: eight meningeal/ependymal enhancement and eight focal enhancing lesions. Twenty-one of the 103 scans had focal or mass lesions on the precontrast images; in eight of these scans, new information was obtained with Gd-DTPA. Of the 24 patients in both groups where new information was obtained with Gd-DTPA, the information contributed to a change in the clinical care of nine patients. CONCLUSION: Gadolinium-enhanced MR is useful in the management of selected patients with human immunodeficiency virus infection, for example those with symptoms suggesting meningeal involvement, focal brain lesions, or if the unenhanced MR does not explain all the patient's symptoms.