Primary intracranial CNS lymphoma: MR manifestations

We reviewed MR scans of 10 patients with biopsy-proved primary CNS lymphoma. Twenty-five lesions were identified in 10 patients (four with AIDS and six without AIDS). In general, the typical lesion of CNS lymphoma was found to have the following MR characteristics: they were slightly hypointense on T1-weighted images and slightly hyperintense on proton density and T2-weighted images relative to gray matter; they induced mild edema and mild to moderate mass effect. In AIDS patients, 82% of the lesions were smaller than 2 cm in diameter, and were frequently located in the temporal lobes and basal ganglia; they were often multiple. In non-AIDS patients, 75% of the lesions were larger than 2 cm in diameter and were primarily found in the deep parietal lobe; most were solitary.

Cine magnetic resonance imaging for evaluation of congenital heart disease: role in pediatric cardiology compared with echocardiography and angiography

Cine magnetic resonance imaging was used for preoperative and postoperative evaluation of 91 patients with congenital heart disease. Their ages ranged from 6 weeks to 14 years. The quality of study was excellent in 81% of the cases, in which it provided complete documentation of diagnostic features; substantial diagnostic information was provided in another 14%, and the study was nondiagnostic in only 5%. This technique was most useful for evaluating areas of the right ventricle (95%), great arteries (95%), vena cava (94%), and pulmonary venous system (91%). The anatomic delineation of these areas was comparable to that obtained by cineangiography and was superior to echocardiography, especially in postoperative patients. For complex venous anomalies, magnetic resonance imaging provided better anatomic details than did angiography or echocardiography. The capability of multiplanar imaging allows complex angled views through the desired planes of the heart and great vessels. Proper sedation is essential to obtain maximum diagnostic information. Our preliminary experience suggests that this new modality provides excellent anatomic information in infants and children with congenital cardiac defects and will play an increasing role in pediatric cardiac diagnosis.

Rhinocerebral mucormycosis: MR manifestations

Magnetic resonance (MR) examinations of three patients with rhinocerebral mucormycosis are reviewed. The clinical course is outlined and the MR characteristics are analyzed in light of the known pathology. The major MR findings include sinus and orbital disease followed by deep facial extension. Involvement of basal portions of the hemispheres, brain stem, and hypothalamus occurred rapidly following ipsilateral facial or orbital invasion in all three cases. Regions of intracerebral inflammation were hyperintense compared with normal parenchyma on T2-weighted and proton density-weighted images. Septic cavernous sinus and internal carotid artery thrombosis was diagnosed by MR in one case. Magnetic resonance demonstrated partial resolution of intracerebral abnormalities that accompanied clinical improvement in the one surviving patient.

MR and CT of lacunar infarcts

Twenty-two patients with clinical signs and symptoms compatible with lacunar transient ischemic attack or stroke of varying chronicity were evaluated with MR imaging. CT was also performed in 21 of these patients. MR revealed small, deep cerebral lesions in locations appropriate to the clinical symptoms in 19 patients. Lacunar infarcts were imaged by CT in 11 patients; however, no lesions were identified on CT that were not detected with MR. Presumed lacunar infarcts were identified on MR images in 17 additional patients. Lacunae generally appeared as focal areas of decreased signal intensity on T1-weighted images and as focal areas of increased signal intensity on T2-weighted images. T2-weighted MR images detected a greater number of lacunar infarcts than did mixed T1-/T2-weighted images, which in turn detected more lacunae than did T1-weighted images. In general, acute lacunar infarcts (within 1 week of onset or recurrence of clinical symptoms) were seen only on T2-weighted images, while chronic lesions (more than 1 week) were seen on both T1- and T2-weighted images. Our results indicate that MR is superior to CT for evaluating lacunar infarcts, and second, that T2-weighted images are more sensitive than T1- and mixed T1-/T2-weighted images for detecting lacunar infarcts.

Human immunodeficiency virus-associated neurobehavioural disorder

AIDS, ARC, and other HIV-associated diseases were originally conceptualised exclusively in terms of defects in cell-mediated immunity and its consequences. But it is now becoming clear that HIV disease can also be a primary neuropsychiatric disorder, although the precise mechanism by which the retrovirus causes impairment in brain function and, ultimately, structural brain damage, remains obscure. The work presented here indicates another shift in our thinking concerning HIV infection. Until recently it was believed that neurological and neuropsychiatric phenomena tended to occur in the late stages of HIV disease. While that might be true for the more severe form of symptomatology that has been termed the AIDS dementia complex, we believe there is at least preliminary evidence that cognitive change can occur earlier in the course of illness, perhaps even in some medically asymptomatic HIV+ individuals. Other investigators have also noted increased neuropsychological abnormality in patients before they developed AIDS or ARC. For example, Janssen et al. found that about half their patients with lymphadenopathy syndrome (LAS) had some neuropsychological test deficits. Durara et al. recently reported on cerebral metabolic rates for glucose in seven HIV+ asymptomatic individuals, compared to 10 HIV- controls. Four of the HIV+ individuals had abnormal asymmetry in frontal and temporal regions suggesting focal reduction in cerebral glucose metabolism. Further indirect evidence that virus can enter the central nervous system early in the course of HIV disease comes from the work of McArthur and associates.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired immunodeficiency syndrome. Magnetic resonance patterns of brain involvement with pathologic correlation

Magnetic resonance brain scans of 30 patients with either acquired immunodeficiency syndrome (AIDS) or AIDS-related complex were reviewed. Twenty patients had focally abnormal neurological examination results at the time of scanning. Pathological diagnosis was available in nine. Four patterns of abnormality were observed on T2-weighted images. Multiple discrete high-signal foci (pattern A) were found in patients with toxoplasmosis and progressive multifocal leukoencephalopathy. Large, bilateral patchy to confluent high-signal areas within the white matter (pattern B) represented a white matter encephalitis secondary to cytomegalovirus or human immunodeficiency virus. Generalized enlargement of the cortical sulci and ventricles (pattern C) probably reflected atrophic changes from the chronic human immunodeficiency virus infection and prolonged debilitating illness. Solitary high-signal-intensity lesions (pattern D) suggested a nonviral opportunistic infection. Differential diagnosis of brain abnormalities in patients with AIDS can be assisted by recognition of these characteristic patterns.

MR contrast enhancement of intracranial lesions with Gd-DTPA

Gd-DTPA is a paramagnetic contrast agent for MR that produces enhancement of lesions on T1-weighted images. Since it does not cross the intact blood-brain barrier (BBB), Gd-DTPA enhances only those pathologic processes that are associated with breakdown of the BBB and structures or lesions that are devoid of a BBB. Gd-DTPA improves conspicuity, helps characterize and delineate the extent of lesions, and increases the sensitivity for detection of cerebral abnormalities.

Coccidioidomycotic brain abscess in an HIV-infected man

Images

MR imaging of cerebellopontine angle and internal auditory canal lesions at 1.5 T

The high-field, thin-section (3-5 mm) MR imaging characteristics of 49 cerebellopontine angle and internal auditory canal lesions were reviewed. The diverse abnormalities include 20 acoustic neurinomas, eight neurinomas of other cranial nerves (six involving the fifth cranial nerve and two involving cranial nerves IX-XI), seven meningiomas, five subdural fluid collections, four brainstem tumors with exophytic components, three glomus jugulare tumors, one epidermoid tumor, and one basilar artery aneurysm. T1-, T2-, and proton-density-weighted images were obtained in all cases. T1-weighted images most accurately showed the margins of the seventh and eighth nerves in the internal auditory canal and were most sensitive in detecting small tumors in the cerebellopontine angle. Differentiation of meningioma from acoustic neurinoma by MR was provided most reliably by separation of the meningioma from the porus acusticus and seventh and eighth nerves and not by signal-intensity differences. A hypointense vascular rim was noted on MR in seven of 13 extracanalicular acoustic tumors and in three of seven meningiomas.

Hypoplasia of cerebellar vermal lobules VI and VII in autism

Autism is a neurologic disorder that severely impairs social, language, and cognitive development. Whether autism involves maldevelopment of neuroanatomical structures is not known. The size of the cerebellar vermis in patients with autism was measured on magnetic resonance scans and compared with its size in controls. The neocerebellar vermal lobules VI and VII were found to be significantly smaller in the patients. This appeared to be a result of developmental hypoplasia rather than shrinkage or deterioration after full development had been achieved. In contrast, the adjacent vermal lobules I to V, which are ontogenetically, developmentally, and anatomically distinct from lobules VI and VII, were found to be of normal size. Maldevelopment of the vermal neocerebellum had occurred in both retarded and nonretarded patients with autism. This localized maldevelopment may serve as a temporal marker to identify the events that damage the brain in autism, as well as other neural structures that may be concomitantly damaged. Our findings suggest that in patients with autism, neocerebellar abnormality may directly impair cognitive functions that some investigators have attributed to the neocerebellum; may indirectly affect, through its connections to the brain stem, hypothalamus, and thalamus, the development and functioning of one or more systems involved in cognitive, sensory, autonomic, and motor activities; or may occur concomitantly with damage to other neural sites whose dysfunction directly underlies the cognitive deficits in autism.

MR imaging of brain contusions: a comparative study with CT

Ninety-eight brain contusions in 17 patients served as a data base for a comparative study of MR and CT for defining brain contusions. MR was the more sensitive technique, detecting 98% of the brain contusions compared with only 56% by CT. CT was slightly better for showing hemorrhagic components, documenting 77% of hemorrhages compared with 71% for MR. The appearance of the contusions on MR was variable, depending on the T1- and T2-weighting of the images and the constituents of the contusions, such as edema, hemorrhage, and encephalomalacia. On MR, hemorrhagic components appeared as high signal on T1-weighted images and as either low or high signal on T2-weighted images, depending on the age of the hemorrhage. The approximate ages of hemorrhagic contusions were often suggested by their appearance on T1- and T2-weighted images. CT is very effective for evaluating acute head trauma, but MR is recommended for documenting brain contusions during the subacute and chronic stages of head injuries.

Benefits of Gd-DTPA for MR imaging of intracranial abnormalities

Forty patients with symptoms of intracranial disease were studied with magnetic resonance before and after intravenous injection of gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA). The T1- and T2-weighted images were obtained in all patients. Ninety brain lesions were found in 36 patients, including primary (20 patients) and metastatic (six) tumors, hemorrhage (one), progressive multifocal leukoencephalopathy (one), cysticercosis (one), infarction (four), and postoperative changes (four). Postcontrast images revealed lesions not seen on precontrast scans in eight (20%) patients. Also, the postcontrast images showed a change in appearance of the lesions in 20 (50%) that provided helpful information for assessing the abnormality in 20 cases (50%). Gadolinium-DTPA did not obscure any of the lesions seen on precontrast scans. It improved conspicuity, helped characterize and delineate the extent of lesions, and increased the sensitivity for detection of cerebral abnormalities.

Cine magnetic resonance imaging after surgical repair in patients with transposition of the great arteries

Cine magnetic resonance imaging (MRI) was used for postoperative evaluation of eight patients who underwent intra-atrial baffle procedure for surgical repair of D-transposition of the great arteries (D-TGA). Their ages ranged from 9 months to 8 years. Younger patients were sedated with chloral hydrate (80 to 100 mg/kg) orally. MRI was performed with use of a General Electric Signa system operating at a field strength of 1.5 tesla. A body or head coil was used depending on the size of the patient. Images were obtained by use of a technique of gradient-recalled acquisition in steady state (GRASS) that utilizes a low flip angle and shorter repetition and echo times. Five patients had widely patent venae cavae and three had superior vena caval obstruction at the junction of the right atrium with a dilated azygos vein. There was no evidence of pulmonary venous obstruction in any of the patients. Right ventricular function was assessed in four patients and their ejection fractions ranged from 58% to 81%. Tricuspid and mitral regurgitation were observed in three and two patients, respectively. Both right and left ventricular outflow tracts were well visualized and showed no evidence of obstruction. Cine MRI is an entirely noninvasive, nonionizing, and safe procedure in young patients and appears to be a valuable alternative method for evaluating patients after surgical repair of D-TGA. With advancing technologies and an accumulation of experience with cine MRI, it appears that this new technique will play an important role in patient care for children with congenital heart disease.

Increased detection of intracranial metastases with intravenous Gd-DTPA

Three patients with intracranial metastases were studied with magnetic resonance imaging at 1.5 T before and after intravenous administration of 0.1 mmol/kg gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA). Axial pre- and postcontrast images demonstrated a total of six and 38 metastases, respectively. Of the 35 lesions detected only after administration of contrast material, all were less than 10 mm, and none had evidence of surrounding edema. Lesion conspicuity was comparable on postcontrast mixed (T1, proton density, and T2) images and T1-weighted images, indicating the feasibility of effectively screening for metastases with a single postcontrast spin-echo sequence providing mixed and T2-weighted images. Sagittal and coronal images depicted temporal lobe lesions not seen on axial images. No discomfort, side effects, or complications resulted from the contrast medium. The detection of additional lesions with Gd-DTPA increased the radiologic suspicion of metastatic disease, revealed locations more favorable for biopsy, prompted the search for a primary tumor, and modified therapeutic objectives and methods.

Evidence for early central nervous system involvement in the acquired immunodeficiency syndrome (AIDS) and other human immunodeficiency virus (HIV) infections. Studies with neuropsychologic testing and magnetic resonance imaging

Although a high prevalence of central nervous system disease is seen in persons with the acquired immunodeficiency syndrome (AIDS), the natural history of brain involvement with human immunodeficiency virus (HIV) remains poorly understood. Neuropsychologic evaluations of 55 ambulatory homosexual men revealed abnormalities in 13 of 15 with AIDS, 7 of 13 [corrected] with AIDS-related complex, 7 of 16 [corrected] with HIV-seropositivity only, and 1 of 11 with HIV-seronegativity. Common neuropsychologic problems included impaired abstracting ability, learning difficulties, and slowed speed of information processing. Magnetic resonance imaging had abnormal findings in 9 of 13 patients with AIDS and 5 of 10 patients with AIDS-related complex who were available for scans. The commonest abnormalities were sulcal and ventricular enlargement and bilateral patchy areas of high signal intensity in the white matter. We postulate that central nervous system involvement by HIV may begin early in the course of AIDS and cause mild cognitive deficits in otherwise asymptomatic persons.

MR demonstration of mesencephalic lesions in osmotic demyelination syndrome (central pontine myelinolysis)

A case of CPM/ODS with mesencephalic involvement is presented. The lesions were non-enhancing on CT and were homogeneous and well-defined on MR with prolonged T1- and T2-relaxation times. MR is recommended for imaging the pontomesencephalic demyelinating lesions associated with this disease.

Demonstration by magnetic resonance of symptomatic spinal epidural lipomatosis

In patients with Cushing's syndrome or morbid obesity, excessive accumulation of fat in the hips, upper back, abdomen, and mediastinum is well known (1, 3, 7). Excessive deposition of fat in the epidural space is less common, but must be recognized as a potential cause of neurological deficit (1-8). We report a patient with iatrogenic Cushing's syndrome, in whom magnetic resonance imaging (MRI) established the specific diagnosis of spinal cord compression secondary to excess epidural fat.

Brain magnetic resonance imaging in the evaluation of lacunar stroke

Thirty-one patients with presumed lacunar stroke, recent (18 patients) or remote (13 patients), were evaluated with brain magnetic resonance imaging (MRI). MRI detected small, deep lesions appropriate to symptoms in 23 of the patients (74%) and was diagnostically superior to brain computed tomography (CT) in those cases where both studies were obtained acutely. MRI also appeared useful in distinguishing between acute and chronic ischemic lesions. Especially in the setting of suspected acute lacunar infarction, MRI, when available, should replace CT as the diagnostic imaging procedure of choice.

MR imaging of the scrotum: normal anatomy

High-resolution magnetic resonance (MR) imaging with a surface coil was utilized to evaluate the normal scrotum. Scrotal contents, spermatic canal, and inguinal regions were visualized within the same field of view. Differences in signal intensity in the testis, epididymis, tunica albuginea, fluid, fat, and spermatic cord allowed for clear delineation of these structures in detail. The high contrast and spatial resolution of MR imaging, coupled with the wide field of view and absence of ionizing radiation, make MR imaging well suited for evaluation of the scrotum.

MR imaging of the scrotum: pathologic conditions

The utility of high-resolution magnetic resonance (MR) imaging in studying a variety of intratesticular and extratesticular pathologic conditions was assessed. The high magnetic signal intensity of the testis provided an excellent background for visualization of intratesticular abnormalities. Except for old blood, all intratesticular processes were less intense than testis, especially on T2-weighted images. The visualization of the tunica albuginea is a distinct advantage, allowing its assessment in cases of trauma or testicular tumors. Epididymal and spermatic cord abnormalities were easily recognized. All pathologic conditions were best seen on T2-weighted images acquired in the coronal plane. Balanced images allowed for tissue characterization.

Abnormal neuroanatomy in a nonretarded person with autism. Unusual findings with magnetic resonance imaging

Recent studies of infantile autism using computed tomographic scanning emphasized the importance of studying cases of classic autism (Kanner's syndrome) without complicating conditions such as mental retardation. Computed tomographic scan studies of such patients reported no evidence of anatomical abnormalities of cerebral hemispheres or of subcortical structures, which are defined by landmarks such as the lateral ventricles and lentiform nuclei. Examination of the cerebellum was not mentioned. The most recent postmortem neuropathologic study reported significant cerebellar abnormality, but the study was of a severely retarded autistic individual. Using magnetic resonance imaging, we have found in vivo evidence of a significant and unusual cerebellar malformation in a person with the classic form of autism uncomplicated by mental retardation (current nonverbal IQ = 112), epilepsy, history of drug use, postnatal trauma, or disease. The finding showed hypoplasia of the declive, folium, and tuber in posterior vermis, but not of the anterior vermis, and hypoplasia of only the medial aspect of each cerebellar hemisphere. The right posterior cerebral hemisphere also showed pathologic findings.