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Biomedical subjects

A J Kumar

Publications and source records attributed to A J Kumar.

At least 37 records · Page 2Linked to original sources
PubMed1991

Multicenter study of gadodiamide injection as a contrast agent in MR imaging of the brain and spine.

To evaluate the safety and efficacy of gadodiamide injection, a nonionic gadolinium chelate complex, in magnetic resonance (MR) imaging of the head and spine, a phase II-III trial was conducted in 439 patients with known or suspected lesions in the central nervous system. All patients received gadodiamide injection in a dosage of 0.1 mmol/kg and were monitored; MR images were evaluated for contrast material enhancement. No serious adverse events or clinically important trends in vital signs, laboratory values, or neurologic status were observed. Gadodiamide injection enhanced or facilitated the visualization of lesions in 266 or 353 patients (75.4%) in whom lesions were shown on unenhanced images, enhanced images, or both; in these 266 patients, the diagnosis was changed in 76 patients (28.6%) and facilitated in 190 patients (71.4%). It is concluded that gadodiamide injection is safe and effective for MR imaging of the head and spine in patients with suspected abnormalities of the central nervous system.

Brain↗
PubMed1991

Cortical magnetic resonance imaging changes in elderly inpatients with major depression.

OBJECTIVE: The purpose of the study was to determine if magnetic resonance imaging (MRI) scans of elderly depressed patients differ from MRI scans of age-matched control subjects and age-matched patients with Alzheimer's disease. METHOD: The authors studied 21 patients 60 years or older with major depression, 16 patients with Alzheimer's disease, and 14 age-matched control subjects. RESULTS: Compared to control subjects, depressed patients had greater cerebral sulcal and temporal sulcal atrophy; larger sylvian fissures, lateral ventricles, third ventricles, and temporal horns; and greater severity of subcortical white matter lesions. Depressed patients also had more basal ganglia lesions but similar levels of periventricular hyperintensity. There were no differences between depressed patients with and without delusions on any MRI measure. Depressed patients who received ECT had more temporal horn atrophy and greater subcortical abnormality summary scores than normal subjects. Cortical sulcal atrophy correlated with age at onset of depression. CONCLUSIONS: The findings suggest that elderly hospitalized depressed patients have greater cortical as well as subcortical atrophy and more basal ganglia lesions than age-matched normal control subjects. The correlation of these abnormalities with outcome remains unknown.

Aged↗
PubMed1990

Bright lesions on sellar/parasellar T1-weighted scans.

Eighty-seven patients with sellar and parasellar pathology were evaluated by magnetic resonance imaging to categorize lesions with hyperintensity on T1-weighted images. Postoperative fat packing after transsphenoidal hypophysectomy, intratumoral subacute or chronic hemorrhage in pituitary adenomas, and hemorrhagic or fat-containing craniopharyngiomas accounted for 33 of 35 abnormalities with short T1 values. Forty-three percent of nonsurgically treated pituitary adenomas had subacute intratumoral hemorrhage present. Using T2-weighted images to distinguish fat from subacute hemorrhage and attempting to identify the normal anterior pituitary gland on T1-weighted images may help to differentiate these three entities. T1-weighted images alone were not sufficient to distinguish between all sellar and parasellar masses.

Adenoma↗
PubMed1990

Acquired immunodeficiency syndrome: correlation of radiologic and pathologic findings in the brain.

The appearance on magnetic resonance (MR) and computed tomographic (CT) images of specific central nervous system disorders associated with acquired immunodeficiency syndrome in 12 cases was correlated with autopsy findings. There were three cases of human immunodeficiency virus (HIV) encephalopathy; three, primary lymphoma; three, toxoplasmosis; one, cryptococcosis; one, cytomegalovirus infection; and one, progressive multifocal leukoencephalopathy. MR imaging demonstrated the various cranial lesions more clearly than did CT. On the basis of MR imaging characteristics, HIV encephalopathy could be distinguished from other lesions, particularly progressive multifocal leukoencephalopathy. Basal ganglia were the most common sites of involvement in opportunistic infections and primary lymphoma. Reliable distinguishing features among lesions of the basal ganglia were not found, except for cryptococcal lesions, which had a unique appearance.

AIDS Dementia Complex↗
PubMed1990

Incidental white matter hyperintensities on magnetic resonance imaging in HIV-1 infection. Multicenter AIDS Cohort Study.

Magnetic resonance (MR) scans were performed as part of a prospective neuropsychological study within the Multicenter AIDS Cohort Study. Fifty HIV-1-seronegative men, 85 HIV-1-seropositive men without constitutional symptoms, and 14 with symptomatic HIV disease underwent MR imaging using a uniform protocol. Scans were rated by neuroradiologists blinded to all clinical details except age. The majority of MR scans were normal in all of the clinical groups and no covert mass lesions or diffuse white matter abnormalities were identified. Focal hyperintensities in the white matter were observed in 24% of the HIV-1 seronegatives, 26% of HIV-1 asymptomatic seropositives (CDC II/III), and 17% of those with ARC/AIDS. No significant associations were noted between the white matter hyperintensities and HIV-1 serostatus, neurological abnormalities, CD4 count, alcohol or drug use, hypertension, or smoking. In one individual classified with early HIV-1 dementia, MR demonstrated several hyperintensities in the deep parietal white matter, but at autopsy no microscopic abnormalities corresponding to the MR findings were identified. Our studies imply that focal white matter hyperintensities identified on MR are not specific for HIV-1 infection and are probably incidental and of no clinical significance.

AIDS-Related Complex↗
PubMed1989

Low prevalence of neurological and neuropsychological abnormalities in otherwise healthy HIV-1-infected individuals: results from the multicenter AIDS Cohort Study.

Accurate description of the prevalence of neurological impairment in healthy individuals who are infected with human immunodeficiency virus type 1 (HIV-1) has relevance for public health policy, for employment issues, and for planning future health needs. Within the Multicenter AIDS Cohort Study, we determined the cross-sectional prevalence of neurological abnormalities in 270 HIV-1 seropositive homosexual and bisexual men in Centers for Disease Control Groups II and III, using a control group of 193 HIV-1 seronegative homosexual men. Utilizing a neurological and neuropsychological screening battery, we found no differences in the prevalence of neuropsychiatric symptoms or in neuropsychological performance. One hundred nineteen subjects with abnormalities on screening tests completed additional neuropsychological testing and had neurological examinations. The majority had normal results and the frequency of neurological abnormalities and impaired neuropsychological performance was not significantly increased among HIV-1 seropositive subjects. Most of the abnormalities could be attributed to causes other than HIV-1. One subject had mild HIV-1-related dementia, yielding a prevalence of 3.7:1,000 (95% confidence interval: 0.19-23.7:1,000). Magnetic resonance imaging demonstrated sulcal prominence and focal areas of high signal intensity in white matter in 63% of HIV-1 seropositive subjects and 48% of uninfected control subjects. Abnormalities in cerebrospinal fluid were noted in 23 (85%) of 27 HIV-1-infected individuals. Our studies indicate that the prevalence of dementia and other HIV-1-related neurological disorders is very low among healthy HIV-1 seropositive homosexual men. The confounding effects of factors such as substance abuse or preexisting medical conditions must be considered in the neurological evaluation of such patients.

AIDS Dementia Complex↗
PubMed1989

Pituitary adenomas: possible role of bromocriptine in intratumoral hemorrhage.

Magnetic resonance (MR) images of 68 patients examined for adenomas of the pituitary gland were retrospectively reviewed for the presence of hyperintensity on T1-weighted images because of recent reports suggesting that bromocriptine treatment may affect T1 values. Twenty-seven patients were examined after either surgery or radiation therapy, 29 were receiving bromocriptine, and 22 had not received any treatment at the time of MR imaging. MR imaging criteria showed evidence of subacute or chronic intratumoral hemorrhage in 18 patients, five of whom had hemorrhage proved at surgery. Ten of the 18 patients were asymptomatic from the hemorrhage; eight had headaches, visual field cuts, or cranial nerve deficits. Although an increased frequency of intratumoral hemorrhage was noted in prolactinomas and macroadenomas and in patients undergoing bromocriptine therapy, the effect of bromocriptine on bleeding was the only significant correlation (P less than .01).

Adenoma↗
PubMed1988

Preliminary communication: neuroanatomical variations of the posterior fossa in men with the fragile X (Martin-Bell) syndrome.

Four men with fragile X (fra (X], or Martin-Bell, syndrome were studied by magnetic resonance imaging (MRI) to determine whether detectable abnormalities of the cerebellum were present. The cerebellum was chosen because of the apparently increased tendency for fra (X) patients to demonstrate autistic behavior and accumulating evidence implicating cerebellar abnormalities in autism. Compared with a control group of four normal men, fra (X) patients had a significantly decreased area of the cerebellar vermis, particularly the posterior portion, on planimetric analysis in the midsagittal plane. The pons and fourth ventricular areas also were decreased and increased, respectively, in the fra (X) men. Neuroanatomical and animal research increasingly implicates the cerebellar vermis as an important component in functional brain systems subserving sensory and motor integration, learning, and modulation of affect, motivation, and social behavior. Thus, vermis dysfunction could account for many of the behavioral and cognitive abnormalities observed in fra (X) males, particularly those which overlap with the behavioral syndrome of autism.

Adult↗
PubMed1988

Fungal sinusitis: diagnosis with CT and MR imaging.

Of 293 patients who underwent computed tomography (CT), surgery, and pathologic examination for chronic sinusitis, 25 had a diagnosis of fungal sinusitis at pathologic examination. Of these, 22 had foci of increased attenuation at CT (in four patients the mean representative CT number [Hounsfied unit] was 122.2 HU [SD, 8.2 HU]), and three did not. Of the 22, 19 patients (76%) met the CT criterion of this study (there was a 12% false-positive and a 12% false-negative diagnostic rate). Six of the 19 patients and one additional patient underwent magnetic resonance (MR) imaging, and all demonstrated remarkably hypointense signal characteristics on T2-weighted images. The findings at MR imaging therefore appear more characteristic of fungal sinusitis than the findings at CT. Furnace atomic absorption spectrometry showed increased concentrations of iron and manganese in mycetoma compared with their concentrations in bacterially infected mucus. This finding and the presence of calcium in the fungal concretion may explain the hypointense T2-weighted signal on MR images.

Adult↗
PubMed1988

Physiologic mucosal changes within the nose and ethmoid sinus: imaging of the nasal cycle by MRI.

Magnetic resonance studies frequently demonstrate increased T2-weighted signal in the nasal area. To further evaluate this phenomenon, several MRI examinations of the nasal cavity were performed within an 8- to 12-hour period. The study demonstrated that changes alternated from side to side and were interrupted by the administration of topical vasoconstriction, confirming imaging of the normal nasal cycle. Changes were also observed within the ethmoid sinuses. Signal intensity on T2-weighted images during the congested phase was similar to inflammatory mucosa. Occasionally, these changes make interpretation of the extent of pathology difficult in patients with sinus disease, and raise the possibility of inflammatory pathology in asymptomatic patients. Awareness of MRI imaging of nasal cycle should reduce the likelihood of diagnostic errors and provides another method for study of this physiologic phenomenon.

Adult↗
PubMed1987

Intraoperative CT monitoring during stereotactic brain surgery.

This paper reports our experience in performing the entire stereotactic surgical procedure with a CT scanner, which shows that target shifting can occur as the probe approaches the target. Therefore, when sampling of small targets or specific sites within larger targets is desired. CT confirmation of the probe's position ensures that the specific area seen on CT is biopsied.

Adolescent↗
PubMed1987

Magnetic resonance planned thalamotomy followed by X-ray/CT-guided thalamotomy.

Magnetic resonance imaging (MRI) is currently the optimal neuroradiologic technique for visualizing the anterior and posterior commissure for defining the AC-PC line. CT is the optimal technique for electrode and probe guidance during stereotactic thalamotomy. Various possibilities of transferring or overlying MRI and CT are outlined which in some future might result in more refined methods of CT-MRI guidance for stereotactic surgery.

Humans↗
PubMed1987

Paranasal sinuses: CT imaging requirements for endoscopic surgery.

Recent advances in the understanding of mucociliary activity and the pathophysiology of the nasal cavity and paranasal sinuses have revolutionized the surgical management of chronic and/or recurrent sinusitis. Meticulous radiographic delineation of the small structures in this region, coupled with endoscopic evaluation, provides detailed preoperative information regarding morphology and pathology. This information has led to more focused endoscopic surgical procedures, which have dramatically reduced patient morbidity. As a consequence, there is now worldwide interest among otolaryngologists in the radiologic definition of paranasal regional anatomy. For effective interactions between radiologist and otolaryngologist, the former must be prepared to render interpretations that address these "microanatomic" locales. This communication is directed at familiarizing the radiologist with these observations and concepts, considering both normal and disturbed anatomy with their attendant pathophysiologic and therapeutic implications.

Endoscopy↗
PubMed1987

Adrenoleukodystrophy: correlating MR imaging with CT.

The effect on the brain of the sex-linked recessive form of adrenoleukodystrophy was studied in 40 boys, 4-18 years old. All underwent computed tomography (CT) scanning; six underwent magnetic resonance (MR) imaging. MR showed a high sensitivity in demonstrating white matter disease. Auditory pathway disease was characterized as involvement of the lateral lemniscus and medial geniculate body, and visual pathway disease was characterized by lateral geniculate body, Meyer loop, and optic radiation involvement. Contrast-enhanced CT still proved to have a greater capacity (at this time) to show the active, advancing form of the disease and concomitant calcifications. This large CT series also demonstrated the broad and variable expressions of adrenoleukodystrophy, which allowed the unification of previously described atypical forms of the disease.

Adolescent↗